fix(5 A5-1/A5-2): bridge commit status posting + enroll custom-html-tiny

A5-2: bridge.py now posts Gitea commit statuses on the recipe PR's head SHA:
- pending on build trigger (so testme-on-pr.sh sees the run immediately)
- success/failure on build finish (so testme-on-pr.sh returns VERDICT=GREEN/RED)
Added post_commit_status() using the existing _api() helper + GITEA_TOKEN.
Called from process_testme() (pending) and watch_and_reflect() (terminal state).

A5-1: added recipe-maintainers/custom-html-tiny to bridge POLL_REPOS in
bridge.nix so !testme on custom-html-tiny PRs is picked up by the bridge poller.

machine-docs/JOURNAL-5.md

@@ -0,0 +1,27 @@
+# JOURNAL — cc-ci Phase 5
+
+## 2026-05-31 — Phase 5 boot
+
+Phase 5 starting. System state verified:
+- cc-ci: `systemctl is-system-running` → running; 0 failed units
+- Docker services: ccci-bridge 1/1, ccci-dashboard 1/1, drone 1/1, traefik 1/1
+- Bridge: 1/1 (container-based, logs via `docker service logs ccci-bridge_app`)
+
+**Sandbox recipe chosen:** `custom-html-tiny` (simple static-web-server; short timeouts; existing
+install_steps.sh hook; generic harness; ideal for upgrade-flow testing with minimal CI runtime).
+
+**Existing open PRs on custom-html-tiny mirror:**
+- #1 `serve-hidden-files` branch — "chore: publish 1.0.2+2.38.0 release" (feature + version bump,
+  NOT from upstream main, NOT merged upstream, from 2026-05-25). Will be closed as superseded when
+  we open the upgrade PR (expected V7 behavior).
+
+**Available upgrades for custom-html-tiny:**
+- `app` service (joseluisq/static-web-server): 2.38.0 → 2.42.0
+- `git` service (alpine/git, compose.git-pull.yml): v2.36.3 → v2.52.0
+- New version label: 1.1.0+2.42.0
+
+## 2026-05-31 — V3: recipe-upgrade flow starting
+
+Following SKILL.md procedure for /recipe-upgrade custom-html-tiny:
+Step 1 (Plan): fetched recipe, found upgrades available — see above.
+Step 2 (Implement): upgrading image tags on cc-ci; bumping version label; committing.