Remove Content Pipeline system from the public repo

Removed by request - it was the one unfinished system in the repo,
and it's the user's call on what represents them publicly. Removed
completely: the README section, docs/content-pipeline.md, and the
two stacks that only existed to back it (postiz, nocodb-content).
Fixed cross-links in dns-naming.md and firewall-and-network.md that
pointed at it (replaced the public-facing-app example with the
still-present Ghost blog), and notifications.md (dropped the
reference, also fixed a leftover 'documented rather than hidden'
phrase in the same paragraph). Stat strip and stack counts updated
(55->53 stacks, 16->15 systems).

README.md

@@ -5,8 +5,8 @@ Most homelabs are a media server with some extra apps bolted on. This one is a p
 <table>
 <tr>
 <td align="center"><strong>11</strong><br/>fleet hosts</td>
-<td align="center"><strong>55</strong><br/>compose stacks</td>
-<td align="center"><strong>16</strong><br/>documented systems</td>
+<td align="center"><strong>53</strong><br/>compose stacks</td>
+<td align="center"><strong>15</strong><br/>documented systems</td>
 <td align="center"><strong>4</strong><br/>trust boundaries</td>
 <td align="center"><strong>13</strong><br/>automated maintenance flows</td>
 </tr>
@@ -117,10 +117,6 @@ One custom-built dashboard aggregates fourteen different data sources — securi
 Every scheduled job across the fleet — orchestration flows, system timers, app-internal schedules — lives in one inventory, visualized as a load heatmap weighted by actual resource impact, so a new job's time slot can be picked without colliding with existing load.
 → [docs/cron-scheduler.md](docs/cron-scheduler.md)
 
-### 📝 Content Pipeline
-A structured content tracker, an automation layer, and a self-hosted blog already work together end to end to take an idea from draft to published post. The one piece still being built is automatic fan-out to social platforms — included here in progress, not hidden until finished.
-→ [docs/content-pipeline.md](docs/content-pipeline.md)
-
 ### 🏗️ Infrastructure as Code
 Packer builds a hardened base image, Terraform provisions each VM from it, and Ansible configures and continuously re-hardens every host after that — three tools, three separate responsibilities, connected by one tag that threads through all three stages instead of one tool trying to do every job.
 → [docs/iac-pipeline.md](docs/iac-pipeline.md)
@@ -131,7 +127,7 @@ Three independent recovery layers cover three different kinds of loss — a lost
 
 ## What's running
 
-~55 Docker Compose stacks, grouped by purpose rather than by which host happens to run them — see [`stacks/`](stacks/): identity & security, platform/infra, media, productivity, and dev tools.
+53 Docker Compose stacks, grouped by purpose rather than by which host happens to run them — see [`stacks/`](stacks/): identity & security, platform/infra, media, productivity, and dev tools.
 
 ---