feat(pipeline): G2 Compliance Commit Ledger — code↔control audit trail

New table: compliance_commits (commit hash, affected controls, risk level)
New API:
  POST /v1/compliance-commits (SDK registers commit + impact)
  GET /v1/compliance-commits (list with filters)
  GET /v1/compliance-commits/by-control/{id} (all commits for a control)
  GET /v1/compliance-commits/stats (dashboard)
  GET /v1/compliance-commits/{id} (detail)

GIN index on affected_control_ids for fast @> containment queries.
454 tests pass, 0 regressions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

control-pipeline/api/__init__.py

@@ -7,6 +7,7 @@ from api.dependency_routes import router as dependency_router
 from api.master_control_routes import router as master_control_router
 from api.decision_trace_routes import router as decision_trace_router
 from api.decision_trace_routes import full_trace_router
+from api.compliance_commit_routes import router as compliance_commit_router
 
 router = APIRouter()
 router.include_router(generator_router)
@@ -16,3 +17,4 @@ router.include_router(dependency_router)
 router.include_router(master_control_router)
 router.include_router(decision_trace_router)
 router.include_router(full_trace_router)
+router.include_router(compliance_commit_router)