Implement 現地現物 (Genchi Genbutsu) post-completion verification:
- Add bin/genchi-genbutsu.sh performing 5 world-state checks:
1. Branch exists on remote
2. PR exists
3. PR has real file changes (> 0)
4. PR is mergeable
5. Issue has a completion comment from the agent
- Wire verification into all agent loops:
- bin/claude-loop.sh: call genchi-genbutsu before merge/close
- bin/gemini-loop.sh: delegate existing inline checks to genchi-genbutsu
- bin/agent-loop.sh: resurrect generic agent loop with genchi-genbutsu wired in
- Update metrics JSONL to include 'verified' field for all loops
- Update burn monitor (tasks.py velocity_tracking):
- Report verified_completion count alongside raw completions
- Dashboard shows verified trend history
- Update morning report (tasks.py good_morning_report):
- Count only verified completions from the last 24h
- Surface verification failures in the report body
Fixes#348
Refs #345
