Add Depone V109 Agent Fabric capture bridge

[moonweave]

Summary

• Adds a passive V109 Agent Fabric capture bridge that emits agent-fabric-capture-manifest contracts.
• Keeps self-report-only manifests at A0-claims-only and allows A1-local-observed only from hash-bound Depone observer capture.
• Validates tampered observer capture, stale fixture hashes, and unexpected touched/diff files as fail-closed cases.
• Ships a shell capture manifest fixture and adds validate-contracts dispatch support.

Safety boundary

• No live model calls.
• No bridge-side command execution.
• Agent self-report remains non-authoritative unless a Depone observer supplies local observations.
• A1 requires observer capture for diff summary, touched files, test output, and command receipts.

Verification

• python3 -m py_compile depone/agent_fabric/capture_bridge.py depone/agent_fabric/reference_adapter.py depone/agent_fabric/__init__.py depone/cli/validate_contracts.py
• python3 tests/test_agent_fabric_capture_bridge.py
• python3 tests/test_agent_fabric_reference_adapter.py
• python3 -c 'from depone.agent_fabric.capture_bridge import _self_test; _self_test()'
• python3 -m depone compile --self-test
• python3 -m depone validate-contracts --self-test
• python3 -m depone validate-contracts --all
• git diff --check
• python3 scripts/check_contract.py --tier changed
• python3 scripts/check_contract.py
• strict staged-files secret assignment scan: no matches