Merge remote-tracking branch 'origin/main' into feat/oauth2-proxy-auth-failure-visible

# Conflicts:
#	runbooks/kustomization.yaml

runbooks/README.md

@@ -135,6 +135,22 @@ Each affected runbook says so on its own page and gives the by-hand equivalent.
   plex.tv/claim — so it is a timed sequence, scripted as `infra/plex/claim-ship.sh`:
   token → `sops` → PR → gate → merge → **forced** `flux reconcile` → pod roll (~2m45s measured).
   Includes why a changed Secret does not restart anything, and why an expired token is harmless.
+- **`plex-quicksync`** — hardware transcoding on the host iGPU. GitOps puts `/dev/dri` in the pod
+  (`hardware.gpu: intel-quicksync`); **a human still has to tick Settings → Transcoder → "Use hardware
+  acceleration when available"**, and no environment variable can do it (the image supports no
+  `PLEX_PREFERENCE*`, verified). The page names the real preference key (`HardwareAcceleratedCodecs`,
+  read out of the binary), says which widely-cited key **does not exist**, and is explicit that the
+  **only** proof is `Transcode (hw)` on the Plex dashboard — Plex renders no ServiceMonitor, so no
+  alert could ever fire. Also: the device-cgroup failure to expect first and its device-plugin
+  fallback, and why a `:latest` pull can silently break it.
+- **`oauth2-proxy-session`** — a gated UI loads but its saves quietly do nothing, and you are never
+  re-prompted to log in. Tells the three stacked auth layers apart from the sidecar's own access log
+  (the four lines that matter, including the upstream `-` that means the proxy answered a request the
+  app never saw). Covers the cookie collision between per-app sidecars sharing the default
+  `_oauth2_proxy` name on `.home.keithjackson.dev` — which deletes sessions belonging to apps in
+  *other* namespaces and is only legible with two logs side by side — the 5-minute access-token
+  session with no `--cookie-refresh`, and why an XHR answered with a 302 instead of a 401 loses a
+  POST body silently.
 - **`crafty-admin-credential`** — you signed into Keycloak and Crafty *still* asks for a password.
   Expected: Crafty 4 has no OIDC, so its own local login sits behind the oauth2-proxy gate as a second
   factor. The page tells the two layers apart from the sidecar log, and explains that the bootstrap