Add Phase 10-12 implementation: multi-tenant, marketplace, observability

Major additions:
- marketplace/: Agent template registry with FTS5 search, ratings, versioning
- observability/: Prometheus metrics, distributed tracing, structured logging
- ledger/migrations/: Database migration scripts for multi-tenant support
- tests/governance/: 15 new test files for phases 6-12 (295 total tests)
- bin/validate-phases: Full 12-phase validation script

New features:
- Multi-tenant support with tenant isolation and quota enforcement
- Agent marketplace with semantic versioning and search
- Observability with metrics, tracing, and log correlation
- Tier-1 agent bootstrap scripts

Updated components:
- ledger/api.py: Extended API for tenants, marketplace, observability
- ledger/schema.sql: Added tenant, project, marketplace tables
- testing/framework.ts: Enhanced test framework
- checkpoint/checkpoint.py: Improved checkpoint management

Archived:
- External integrations (Slack/GitHub/PagerDuty) moved to .archive/
- Old checkpoint files cleaned up

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

agents/tier1-agent/run-agent.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+#
+# Run the Tier 1 Agent
+#
+# Usage:
+#   ./run-agent.sh status
+#   ./run-agent.sh exec ls -la
+#   ./run-agent.sh tf-plan /path/to/terraform
+#
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+# Set session ID if not set
+export SESSION_ID="${SESSION_ID:-session-$(date +%Y%m%d-%H%M%S)}"
+
+# Run agent
+exec python3 "${SCRIPT_DIR}/agent.py" "$@"