Move the deployment runbook out of the repository into CTXD

By owner directive (2026-10-08), all runbook information lives in the
CTXD project mealquest, file RUNBOOKS.MD, never in the repository.
Delete deploy/RUNBOOK.md, whose content is merged into that CTXD file,
and point the comments in deploy/.env.example, deploy/compose.yaml and
deploy/systemd/mealquest-media-backup.sh at RUNBOOKS.MD instead.

Maestro task e81ed994-a510-48e6-9cf6-e76d5d81f56c.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

deploy/.env.example

@@ -57,10 +57,10 @@ MEALQUEST_OIDC_ALLOWED_GROUPS=mealquest-admin
 
 # --- Google Calendar (Push to Calendar) ------------------------------------
 
-# Client ID of the Google OAuth web client (deploy/RUNBOOK.md "Google
-# Calendar OAuth client"). Required: the service will not start without it
-# and the client secret file. Its authorized redirect URI is
-# <MEALQUEST_PUBLIC_URL origin>/api/v1/integrations/google/callback.
+# Client ID of the Google OAuth web client (CTXD project mealquest,
+# RUNBOOKS.MD "Google Calendar OAuth client"). Required: the service will
+# not start without it and the client secret file. Its authorized redirect
+# URI is <MEALQUEST_PUBLIC_URL origin>/api/v1/integrations/google/callback.
 MEALQUEST_GOOGLE_CLIENT_ID=<client id>.apps.googleusercontent.com
 
 # Optional session lifetimes. A session ends after IDLE unused and always MAX
@@ -82,7 +82,7 @@ MEALQUEST_SESSION_MAX=4320h
 #   The SearXNG recipe-search sidecar on the compose network. The Settings
 #   screen pre-fills it as the SearXNG URL until one is saved; the saved
 #   provider and base URL come from PATCH /api/v1/settings/recipe-search.
-#   See deploy/RUNBOOK.md "Recipe search (SearXNG)".
+#   See CTXD project mealquest, RUNBOOKS.MD "Recipe search (SearXNG)".
 
 # --- Planned; not read by the service yet -------------------------------------
 #