docs: fix secrets-lifecycle label backgrounds via labelBackgroundColor

Root cause was the edge's own labelBackgroundColor style property,
left enabled with no explicit value in the app, distinct from the
label's HTML text styling entirely. Set it explicitly to #1C1D1E,
then stripped a competing plain-white background layer draw.io's
export was still injecting on top of it.

assets/secrets-lifecycle.svg

@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- Do not edit this file with editors other than draw.io -->
 <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
-<svg xmlns="http://www.w3.org/2000/svg" style="background: transparent; background-color: transparent; color-scheme: light dark;" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="1312px" height="393px" viewBox="0 0 1312 393" id="ge-svg--V1X9sds1eUqciFZ7Vvy" content="&lt;mxfile host=&quot;embed.diagrams.net&quot; scale=&quot;1&quot; border=&quot;0&quot;&gt;&#10;  &lt;diagram name=&quot;Secret Lifecycle&quot; id=&quot;secret-lifecycle-1&quot;&gt;&#10;    &lt;mxGraphModel dx=&quot;1414&quot; dy=&quot;791&quot; grid=&quot;1&quot; gridSize=&quot;10&quot; guides=&quot;1&quot; tooltips=&quot;1&quot; connect=&quot;1&quot; arrows=&quot;1&quot; fold=&quot;1&quot; page=&quot;1&quot; pageScale=&quot;1&quot; pageWidth=&quot;1340&quot; pageHeight=&quot;620&quot; math=&quot;0&quot; shadow=&quot;0&quot;&gt;&#10;      &lt;root&gt;&#10;        &lt;mxCell id=&quot;0&quot; /&gt;&#10;        &lt;mxCell id=&quot;1&quot; parent=&quot;0&quot; /&gt;&#10;        &lt;mxCell id=&quot;agent&quot; parent=&quot;1&quot; style=&quot;rounded=1;whiteSpace=wrap;html=1;fillColor=#e1d5e7;strokeColor=#9673a6;fontColor=#333333;fontSize=14;fontStyle=1;shadow=1;&quot; value=&quot;Vault Agent&amp;lt;br&amp;gt;&amp;lt;font style=&amp;quot;font-size:11px&amp;quot;&amp;gt;runs on the consuming host&amp;lt;/font&amp;gt;&quot; vertex=&quot;1&quot;&gt;&#10;          &lt;mxGeometry height=&quot;90&quot; width=&quot;200&quot; x=&quot;40&quot; y=&quot;260&quot; as=&quot;geometry&quot; /&gt;&#10;        &lt;/mxCell&gt;&#10;        &lt;mxCell id=&quot;vault&quot; parent=&quot;1&quot; style=&quot;rounded=1;whiteSpace=wrap;html=1;fillColor=#e1d5e7;strokeColor=#9673a6;fontColor=#333333;fontSize=14;fontStyle=1;shadow=1;&quot; value=&quot;Vault&amp;lt;br&amp;gt;&amp;lt;font style=&amp;quot;font-size:11px&amp;quot;&amp;gt;server&amp;lt;/font&amp;gt;&quot; vertex=&quot;1&quot;&gt;&#10;          &lt;mxGeometry height=&quot;90&quot; width=&quot;200&quot; x=&quot;380&quot; y=&quot;260&quot; as=&quot;geometry&quot; /&gt;&#10;        &lt;/mxCell&gt;&#10; 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edge=&quot;1&quot; parent=&quot;1&quot; source=&quot;agent&quot; style=&quot;html=1;endArrow=block;strokeColor=#9673a6;fontColor=#9673a6;fontSize=11;rounded=1;edgeStyle=orthogonalEdgeStyle;exitX=0.3;exitY=0;exitDx=0;exitDy=0;entryX=0.5;entryY=0;entryDx=0;entryDy=0;&quot; target=&quot;vault&quot; value=&quot;&amp;lt;font style=&amp;quot;font-size: 13px;&amp;quot;&amp;gt;① authenticate — AppRole (role_id + secret_id)&amp;lt;/font&amp;gt;&quot;&gt;&#10;          &lt;mxGeometry relative=&quot;1&quot; x=&quot;0.0023&quot; as=&quot;geometry&quot;&gt;&#10;            &lt;mxPoint as=&quot;offset&quot; /&gt;&#10;            &lt;Array as=&quot;points&quot;&gt;&#10;              &lt;mxPoint x=&quot;100&quot; y=&quot;200&quot; /&gt;&#10;              &lt;mxPoint x=&quot;480&quot; y=&quot;200&quot; /&gt;&#10;            &lt;/Array&gt;&#10;          &lt;/mxGeometry&gt;&#10;        &lt;/mxCell&gt;&#10;        &lt;mxCell id=&quot;s2&quot; edge=&quot;1&quot; parent=&quot;1&quot; source=&quot;vault&quot; style=&quot;html=1;endArrow=block;strokeColor=#9673a6;fontColor=#9673a6;fontSize=11;rounded=1;edgeStyle=orthogonalEdgeStyle;exitX=0.5;exitY=1;exitDx=0;exitDy=0;entryX=0.603;entryY=0.996;entryDx=0;entryDy=0;entryPerimeter=0;&quot; target=&quot;agent&quot; value=&quot;&amp;lt;font style=&amp;quot;font-size: 13px;&amp;quot;&amp;gt;② short-lived token issued, cached, auto-renewed&amp;lt;/font&amp;gt;&quot;&gt;&#10;          &lt;mxGeometry relative=&quot;1&quot; x=&quot;-0.0012&quot; as=&quot;geometry&quot;&gt;&#10;            &lt;mxPoint as=&quot;offset&quot; /&gt;&#10;            &lt;Array as=&quot;points&quot;&gt;&#10;              &lt;mxPoint x=&quot;480&quot; y=&quot;375&quot; /&gt;&#10;              &lt;mxPoint x=&quot;160&quot; y=&quot;375&quot; /&gt;&#10;              &lt;mxPoint x=&quot;160&quot; y=&quot;349.6&quot; /&gt;&#10;            &lt;/Array&gt;&#10;          &lt;/mxGeometry&gt;&#10;        &lt;/mxCell&gtLine truncated
+<svg xmlns="http://www.w3.org/2000/svg" style="background: transparent; background-color: transparent; color-scheme: light dark;" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="1312px" height="393px" viewBox="0 0 1312 393" content="&lt;mxfile host=&quot;embed.diagrams.net&quot; scale=&quot;1&quot; border=&quot;0&quot;&gt;&#10;  &lt;diagram name=&quot;Secret Lifecycle&quot; id=&quot;secret-lifecycle-1&quot;&gt;&#10;    &lt;mxGraphModel dx=&quot;1414&quot; dy=&quot;791&quot; grid=&quot;1&quot; gridSize=&quot;10&quot; guides=&quot;1&quot; tooltips=&quot;1&quot; connect=&quot;1&quot; arrows=&quot;1&quot; fold=&quot;1&quot; page=&quot;1&quot; pageScale=&quot;1&quot; pageWidth=&quot;1340&quot; pageHeight=&quot;620&quot; math=&quot;0&quot; shadow=&quot;0&quot;&gt;&#10;      &lt;root&gt;&#10;        &lt;mxCell id=&quot;0&quot; /&gt;&#10;        &lt;mxCell id=&quot;1&quot; parent=&quot;0&quot; /&gt;&#10;        &lt;mxCell id=&quot;agent&quot; parent=&quot;1&quot; style=&quot;rounded=1;whiteSpace=wrap;html=1;fillColor=#e1d5e7;strokeColor=#9673a6;fontColor=#333333;fontSize=14;fontStyle=1;shadow=1;&quot; value=&quot;Vault Agent&amp;lt;br&amp;gt;&amp;lt;font style=&amp;quot;font-size:11px&amp;quot;&amp;gt;runs on the consuming host&amp;lt;/font&amp;gt;&quot; vertex=&quot;1&quot;&gt;&#10;          &lt;mxGeometry height=&quot;90&quot; width=&quot;200&quot; x=&quot;40&quot; y=&quot;260&quot; as=&quot;geometry&quot; /&gt;&#10;        &lt;/mxCell&gt;&#10;        &lt;mxCell id=&quot;vault&quot; parent=&quot;1&quot; style=&quot;rounded=1;whiteSpace=wrap;html=1;fillColor=#e1d5e7;strokeColor=#9673a6;fontColor=#333333;fontSize=14;fontStyle=1;shadow=1;&quot; value=&quot;Vault&amp;lt;br&amp;gt;&amp;lt;font style=&amp;quot;font-size:11px&amp;quot;&amp;gt;server&amp;lt;/font&amp;gt;&quot; vertex=&quot;1&quot;&gt;&#10;          &lt;mxGeometry height=&quot;90&quot; width=&quot;200&quot; x=&quot;380&quot; y=&quot;260&quot; as=&quot;geometry&quot; /&gt;&#10;        &lt;/mxCell&gt;&#10;        &lt;mxCell id=&quot;disk&quot; parent=&quot;1&quot; style=&quot;shape=cylinder3;whiteSpace=wrap;html=1;fillColor=#F5F5F5;strokeColor=#666666;fontColor=#333333;fontSize=14;fontStyle=1;shadow=1;boundedLbl=1;&quot; value=&quot;Local Disk&amp;lt;br&amp;gt;&amp;lt;font style=&amp;quot;font-size:11px&amp;quot;&amp;gt;rendered file&amp;lt;/font&amp;gt;&quot; vertex=&quot;1&quot;&gt;&#10;          &lt;mxGeometry height=&quot;110&quot; width=&quot;160&quot; x=&quot;620&quot; y=&quot;250&quot; as=&quot;geometry&quot; /&gt;&#10;        &lt;/mxCell&gt;&#10;        &lt;mxCell id=&quot;app&quot; parent=&quot;1&quot; style=&quot;rounded=1;whiteSpace=wrap;html=1;fillColor=#dae8fc;strokeColor=#6c8ebf;fontColor=#333333;fontSize=14;fontStyle=1;shadow=1;&quot; value=&quot;Application&quot; vertex=&quot;1&quot;&gt;&#10;          &lt;mxGeometry height=&quot;90&quot; width=&quot;200&quot; x=&quot;1140&quot; y=&quot;260&quot; as=&quot;geometry&quot; /&gt;&#10;        &lt;/mxCell&gt;&#10;        &lt;mxCell id=&quot;s1&quot; edge=&quot;1&quot; parent=&quot;1&quot; source=&quot;agent&quot; style=&quot;html=1;labelBackgroundColor=light-dark(#FFFFFF,#1C1D1E);endArrow=block;strokeColor=#9673a6;fontColor=#9673a6;fontSize=11;rounded=1;edgeStyle=orthogonalEdgeStyle;exitX=0.3;exitY=0;exitDx=0;exitDy=0;entryX=0.5;entryY=0;entryDx=0;entryDy=0;&quot; target=&quot;vault&quot; value=&quot;&amp;lt;font style=&amp;quot;font-size: 13px;&amp;quot;&amp;gt;① authenticate — AppRole (role_id + secret_id)&amp;lt;/font&amp;gt;&quot;&gt;&#10;          &lt;mxGeometry relative=&quot;1&quot; x=&quot;0.0023&quot; as=&quot;geometry&quot;&gt;&#10;            &lt;mxPoint as=&quot;offset&quot; /&gt;&#10;            &lt;Array as=&quot;points&quot;&gt;&#10;              &lt;mxPoint x=&quot;100&quot; y=&quot;200&quot; /&gt;&#10;              &lt;mxPoint x=&quot;480&quot; y=&quot;200&quot; /&gt;&#10;            &lt;/Array&gt;&#10;          &lt;/mxGeometry&gt;&#10;        &lt;/mxCell&gt;&#10;        &lt;mxCell id=&quot;s2&quot; edge=&quot;1&quot; parent=&quot;1&quot; source=&quot;vault&quot; style=&quot;html=1;labelBackgroundColor=light-dark(#FFFFFF,#1C1D1E);endArrow=block;strokeColor=#9673a6;fontColor=#9673a6;fontSize=11;rounded=1;edgeStyle=orthogonalEdgeStyle;exitX=0.5;exitY=1;exitDx=0;exitDy=0;entryX=0.603;entryY=0.996;entryDx=0;entryDy=0;entryPerimeter=0;&quot; target=&quot;agent&quot; value=&quot;&amp;lt;font style=&amp;quot;font-size: 13px;&amp;quot;&amp;gt;② short-lived token issued, cached, auto-renewed&amp;lt;/font&amp;gt;&quot;&gt;&#10;          &lt;mxGeometry relative=&quot;1&quot; x=&quot;-0.0012&quot; as=&quot;geometry&quot;&gt;&#10;            &lt;mxPoint as=&quot;offset&quot; /&gt;&#10;            &lt;Array as=&quot;points&quot;&gt;&#10;              &lt;mxPoint x=&quot;480&quot; y=&quot;375&quot; /&gt;&#10;              &lt;mxPoint x=&quot;160&quot; y=&quot;375&quot; /&gt;&#10;              &lt;mxPoint x=&quot;160&quot; y=&quot;349.6&quot; /&gt;&#10;            &lt;/ArrayLine truncated