Initial commit: Agent Governance System Phase 8

Phase 8 Production Hardening with complete governance infrastructure:

- Vault integration with tiered policies (T0-T4)
- DragonflyDB state management
- SQLite audit ledger
- Pipeline DSL and templates
- Promotion/revocation engine
- Checkpoint system for session persistence
- Health manager and circuit breaker for fault tolerance
- GitHub/Slack integrations
- Architectural test pipeline with bug watcher, suggestion engine, council review
- Multi-agent chaos testing framework

Test Results:
- Governance tests: 68/68 passing
- E2E workflow: 16/16 passing
- Phase 2 Vault: 14/14 passing
- Integration tests: 27/27 passing

Coverage: 57.6% average across 12 phases

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

preflight/__init__.py

@@ -0,0 +1,27 @@
+"""
+Preflight Check System
+======================
+Phase 3: Execution Pipeline - Preflight Validation
+
+Components:
+- inventory_check: Validates targets exist in allowed pools
+- dependency_check: Verifies secrets and services available
+- sandbox_assert: Ensures targets are within sandbox boundaries
+- preflight: Unified gate combining all checks
+"""
+
+from .inventory_check import InventoryChecker, CheckResult, CheckStatus
+from .dependency_check import DependencyChecker
+from .sandbox_assert import SandboxAsserter, AssertionResult, AssertionStatus
+from .preflight import PreflightGate
+
+__all__ = [
+    "InventoryChecker",
+    "DependencyChecker",
+    "SandboxAsserter",
+    "PreflightGate",
+    "CheckResult",
+    "CheckStatus",
+    "AssertionResult",
+    "AssertionStatus",
+]