feat(server): production cut-over to Bun — notify_review, setup/callback, key resolution

- index.ts: add POST /api/v1/notify_review (queue-worker Discord bridge),
  /setup/callback (GitHub App manifest conversion), error logging on review
  failure, PR_AGENT_APP_DIR-based private key resolution
- config.ts: API key falls back to on-disk omniroute_key (same source as
  run_server.py) when no env key present — fixes 401 in systemd context
- markdown.ts: don't hyperlink non-URL ticket values (N/A)
- secrets.ts: fallback private key from ~/.hermes/keys + omni key ~/.hermes
- pr-queue-worker.py / auto_merge_bot.py: notify_review default port 4002→4023

Deploy: pr-agent-bun.service (Bun binary, port 4023) replaces
pr-agent-server.service (Python, port 4002, disabled). Caddy route updated in
asepharyana/infra (proxy 4023). Verified live: webhook → review → claude-opus-5
→ persistent GitHub comment published after Python shutdown.

scripts/pr-queue-worker.py

@@ -421,7 +421,7 @@ def merge_pr(token, repo_full, pr_num, sha):
 def post_discord_notification(repo_full, pr_num, status, summary="", score="", url=""):
     """Fire-and-forget Discord notification via pr-agent server internal endpoint."""
     import httpx
-    notify_url = os.environ.get("PR_AGENT_NOTIFY_URL", "http://127.0.0.1:4002/api/v1/notify_review")
+    notify_url = os.environ.get("PR_AGENT_NOTIFY_URL", "http://127.0.0.1:4023/api/v1/notify_review")
     try:
         with httpx.Client(timeout=5) as client:
             client.post(notify_url, json={