Fix loop re-processing, branch awareness, and commit message clarity

- Sanitize AI responses by replacing BLIGHT: with BLIGHT: to prevent
  the service's own commits from triggering another processing cycle
- Pass branch (extracted from refs/heads/<branch>) through to Gitea get/update
  calls so pushes to non-default branches are read and written correctly
- Commit message now includes the file path: "BLIGHT: process triggers in <path>"

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gitea_client.py

@@ -10,7 +10,7 @@ def _headers() -> dict:
     }
 
 
-def get_file(owner: str, repo: str, path: str) -> tuple[str, str]:
+def get_file(owner: str, repo: str, path: str, branch: str) -> tuple[str, str]:
     """Fetch a file's decoded content and its SHA from Gitea.
 
     Returns:
@@ -18,7 +18,7 @@ def get_file(owner: str, repo: str, path: str) -> tuple[str, str]:
         required for the subsequent update call.
     """
     url = f"{config.GITEA_URL}/api/v1/repos/{owner}/{repo}/contents/{path}"
-    response = requests.get(url, headers=_headers(), timeout=30)
+    response = requests.get(url, headers=_headers(), params={"ref": branch}, timeout=30)
     response.raise_for_status()
     data = response.json()
     content = base64.b64decode(data["content"]).decode("utf-8")
@@ -31,14 +31,16 @@ def update_file(
     path: str,
     content: str,
     sha: str,
-    commit_message: str = "BLIGHT: process triggers",
+    branch: str,
+    commit_message: str | None = None,
 ) -> None:
     """Write updated file content back to Gitea."""
     url = f"{config.GITEA_URL}/api/v1/repos/{owner}/{repo}/contents/{path}"
     payload = {
-        "message": commit_message,
+        "message": commit_message or f"BLIGHT: process triggers in {path}",
         "content": base64.b64encode(content.encode("utf-8")).decode("ascii"),
         "sha": sha,
+        "branch": branch,
     }
     response = requests.put(url, headers=_headers(), json=payload, timeout=30)
     response.raise_for_status()