fix(agents): replace gh CLI with curl for PR checking to prevent duplicate work

Agents do not have access to gh CLI, causing them to skip the pre-flight
PR check and collide on duplicate work. This replaces all gh-based PR
checking commands with curl + jq using the GitHub REST API, updates the
task claiming protocol to use branch push + started log file as the
primary lock mechanism, and updates automation scripts to use curl for
PR listing and git fetch for PR checkout.

Files updated:
- AGENTS.md (Section 12 coordination rules)
- CLAUDE.md (coordination rules)
- META_PROMPTS.md (daily + weekly meta prompts)
- daily-scheduler.md (pre-flight gate, task claiming, error handling)
- weekly-scheduler.md (pre-flight gate, task claiming, error handling)
- bitvid-pr-review-agent.md (PR enumeration + checkout)
- bitvid-ci-health-agent.md (CI run gathering)
- bitvid-weekly-synthesis-agent.md (PR metadata gathering)
- bitvid-changelog-agent.md (PR metadata verification)
- scripts/agent/review-open-prs.mjs (PR listing + checkout)
- scripts/automated-pr-review.mjs (--all mode PR listing + checkout)

https://claude.ai/code/session_01L5bzzGpZ6YTiLXcfqaL81G

CLAUDE.md

@@ -458,7 +458,11 @@ This project uses multiple AI coding agents working in parallel:
 
 All agents **must** follow the subsystem boundaries and PR discipline rules in `AGENTS.md` Section 12. The key principles:
 
-1. **Check before you start.** Look at open PRs (`gh pr list`) before beginning work. If another agent has an open PR touching the same files, stop and flag the conflict.
+1. **Check before you start.** Look at open PRs before beginning work by running:
+   ```
+   curl -s "https://api.github.com/repos/PR0M3TH3AN/bitvid/pulls?state=open&per_page=100" | jq '{count: length, titles: [.[].title]}'
+   ```
+   If another agent has an open PR touching the same files, stop and flag the conflict.
 2. **One subsystem per PR.** Don't mix unrelated changes. A lint fix and a feature addition are two separate PRs.
 3. **`js/app.js` is single-writer.** Only one PR at a time should modify the main orchestrator.
 4. **Merge fast, branch short.** Long-lived branches cause exponential merge pain with multiple agents. Keep PRs small and mergeable in one sitting.