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.

bridge/bridge.py

@@ -160,6 +160,18 @@ def edit_comment(owner, repo, comment_id, body):
     )
 
 
+def post_commit_status(owner, repo, sha, state, target_url, description=""):
+    """Post a Gitea commit status on a recipe PR's head SHA so testme-on-pr.sh can read
+    the verdict from GET /repos/{owner}/{repo}/commits/{sha}/status (Phase 5 / A5-2 fix)."""
+    _api(
+        f"{GITEA_API}/repos/{owner}/{repo}/statuses/{sha}",
+        GITEA_TOKEN,
+        method="POST",
+        data={"state": state, "target_url": target_url,
+              "description": description, "context": "cc-ci/testme"},
+    )
+
+
 def build_status(num):
     status, b = _api(f"{DRONE_URL}/api/repos/{CI_REPO}/builds/{num}", DRONE_TOKEN, scheme="Bearer")
     return b.get("status") if status == 200 and b else None
@@ -222,6 +234,8 @@ def watch_and_reflect(owner, name, number, num, recipe, sha, comment_id, run_url
         _t.sleep(15)
     if comment_id:
         edit_comment(owner, name, comment_id, result_comment_body(recipe, sha, num, run_url, last))
+    git_state = "success" if last == "success" else "failure"
+    post_commit_status(owner, name, sha, git_state, run_url, f"cc-ci: {git_state}")
     log(f"reflected outcome build {num} ({recipe} PR #{number}): {last}")
 
 
@@ -271,6 +285,7 @@ def process_testme(full_name, owner, name, number, user, comment_id, source, qui
         post_comment(owner, name, number, "cc-ci: failed to start a CI run (see bridge logs).")
         return None, "trigger failed"
     run_url = f"{DRONE_URL}/{CI_REPO}/{num}"
+    post_commit_status(owner, name, head["sha"], "pending", run_url, "cc-ci run in progress")
     mode = " **(--quick: lower-confidence fast lane; does not gate merge)**" if quick else ""
     # R2/U3: one comment per PR, updated in place. Reuse the existing marked comment if present
     # (re-`!testme` refreshes it back to the ⏳ placeholder), else post a new one.