fix: #412/#413/#414 runtime stability and PR governance preflight

## #413 — runtime_verify_monitor.sh pipefail fix
- find_live_pids() now captures pgrep output via local variable with || true
  so pipefail never triggers on no-match (pgrep exit 1)
- Regression test added: monitor survives MAX_LOOPS=1 without crash

## #412 — startup crash logging improvement
- Add asyncio.CancelledError catch in sync_positions_from_broker call
  so BaseException-level cancellations are logged before propagating
- Provides evidence in run log if CancelledError causes future startup aborts

## #414 — PR governance preflight
- validate_pr_body.py: add REQ-ID/TASK-ID/TEST-ID pattern checks (--no-governance flag to skip)
- docs/workflow.md: new "PR Governance Preflight (Mandatory)" section
- docs/commands.md: "PR Body Governance Preflight" section before tea pulls create
- Tests: 4 new governance traceability tests in test_validate_pr_body.py

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

tests/test_validate_pr_body.py

@@ -37,6 +37,7 @@ def test_validate_pr_body_text_allows_escaped_newline_in_code_blocks() -> None:
         [
             "## Summary",
             "- example uses `\\n` for explanation",
+            "- REQ-OPS-001 / TASK-OPS-001 / TEST-OPS-001",
             "```bash",
             "printf 'line1\\nline2\\n'",
             "```",
@@ -63,7 +64,7 @@ def test_validate_pr_body_text_passes_with_valid_markdown() -> None:
     text = "\n".join(
         [
             "## Summary",
-            "- item",
+            "- REQ-OPS-001 / TASK-OPS-001 / TEST-OPS-001",
             "",
             "## Validation",
             "```bash",
@@ -74,6 +75,34 @@ def test_validate_pr_body_text_passes_with_valid_markdown() -> None:
     assert module.validate_pr_body_text(text) == []
 
 
+def test_validate_pr_body_text_detects_missing_req_id() -> None:
+    module = _load_module()
+    text = "## Summary\n- TASK-OPS-001 / TEST-OPS-001 item\n"
+    errors = module.validate_pr_body_text(text)
+    assert any("REQ-ID" in err for err in errors)
+
+
+def test_validate_pr_body_text_detects_missing_task_id() -> None:
+    module = _load_module()
+    text = "## Summary\n- REQ-OPS-001 / TEST-OPS-001 item\n"
+    errors = module.validate_pr_body_text(text)
+    assert any("TASK-ID" in err for err in errors)
+
+
+def test_validate_pr_body_text_detects_missing_test_id() -> None:
+    module = _load_module()
+    text = "## Summary\n- REQ-OPS-001 / TASK-OPS-001 item\n"
+    errors = module.validate_pr_body_text(text)
+    assert any("TEST-ID" in err for err in errors)
+
+
+def test_validate_pr_body_text_skips_governance_when_disabled() -> None:
+    module = _load_module()
+    text = "## Summary\n- item without any IDs\n"
+    errors = module.validate_pr_body_text(text, check_governance=False)
+    assert not any("REQ-ID" in err or "TASK-ID" in err or "TEST-ID" in err for err in errors)
+
+
 def test_fetch_pr_body_reads_body_from_tea_api(monkeypatch) -> None:
     module = _load_module()