Add action/session level MCP interaction logging

[ansalls]

Motivation

• Provide per-interaction observability for MCP operations so activity can be traced by origin and correlated across systems for debugging and security audits.
• Surface stable correlation identifiers (action_id, session_id) at the tool-invocation boundary and forward them to downstream services.

Description

• Generate and propagate correlation IDs: MCPServer.call_tool now generates action_id/session_id (and accepts caller-provided session_id/source) and returns them on every ToolCallResponse.
• Add lifecycle logging in app/domains/mcp_server/server.py for tool invocation events (started, not_found, missing_argument, succeeded, failed) and endpoint-level logs for /mcp/tools and /mcp/resources including source IP and path metadata.
• Add outbound HTTP client logs and header propagation in app/domains/mcp_server/client.py via mcp_outbound_request, mcp_outbound_response, and mcp_outbound_error, and forward X-MCP-Action-ID and X-MCP-Session-ID on requests.
• Update unit tests to assert presence and propagation of action_id/session_id and update docs (README.md, ARCHITECTURE.md, AI_CHANGE_CHECKLIST.md) to document the traceability behavior.

Testing

• Unit tests: ran python -m pytest tests/unit/test_mcp_client_unit.py tests/unit/test_mcp_server_unit.py -q and all tests passed (9 passed).
• Project checks: attempted make lint and make typecheck but the environment is missing local virtualenv tools (.venv/bin/ruff, .venv/bin/mypy) so these targets could not run to completion.
• Security and full test gate: attempted make audit-security and make test but these failed in the current environment due to missing docker and .venv/bin/pytest respectively, which are environmental blockers rather than code failures.

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Codex Task