Add cheatsheets section (Proxmox CLI, zsh config reference)

Lower-bar reference material, distinct from docs/'s engineering write-ups:
recovered Proxmox cheat sheets (live-verified against PVE 9.2.21, new
remote-migrate/importovf/pvesm subcommands added, acmedomain0 flag typo
fixed) plus the real zsh aliases/functions/keybindings from the actual
ZDOTDIR-based config.

cheatsheets/README.md

@@ -0,0 +1,13 @@
+# Cheatsheets
+
+Quick-reference material, not deep dives. The [`docs/`](../docs/) directory is
+where the real engineering write-ups live — verified claims, real evidence,
+the actual design decisions behind each system. This directory is lower-key:
+command references and config notes for tools I use day-to-day, kept here so
+they're easy to find and easy to add to.
+
+- **[proxmox/](proxmox/)** — CLI cheat sheet for the hypervisor cluster this
+  fleet runs on (`qm`/`pct`/`pvesm`/`pveam`), plus API token auth and
+  certificate management notes.
+- **[zsh/](zsh/)** — the aliases, functions, and keybindings from my actual
+  zsh config, not a generic zsh tutorial.