docs: sync project guides to the new CI flow

Aligns the project guides with the branching/CI/environment changes
landed in the previous commits:

- CLAUDE.md: per-stage CI gate now closes against gitea.lan; describes
  the main/development/feature/* flow and the workflow surface
- docs/ARCHITECTURE.md: new section 18 "CI and Environments" covering
  branches, workflows, and the local-dev / dev-deploy / local-ci
  triad; section numbering shifted accordingly
- tools/local-ci/README.md: marked as fallback (offline / runner
  isolation only)
- tools/local-dev/README.md and ui/README.md: cross-link to
  tools/dev-deploy/ for production-shaped testing

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/README.md

@@ -153,6 +153,12 @@ The stack accepts a fixed dev code (`123456`) in addition to the
 real Mailpit-delivered one. Full runbook in
 [`../tools/local-dev/README.md`](../tools/local-dev/README.md).
 
+For testing the production-shaped surface — Caddy in front of the
+gateway, statically served UI bundle, real `https://*.galaxy.lan`
+hostnames — use the long-lived dev environment at
+[`../tools/dev-deploy/`](../tools/dev-deploy/README.md). It is
+redeployed by Gitea Actions on every merge into `development`.
+
 ## Per-phase docs
 
 Topic docs live under `ui/docs/` and are added per phase as they're