feat(4.10): P4 integration tests — capstone verification (#38)

* feat(4.10): P4 integration tests — 26 outcome-focused tests

- 5 sections: facade, MCP server, cross-module, backward-compat, architecture
- Verifies all 4 MCP tools register with correct names
- Tests result formatting roundtrip (format → JSON → parse)
- Validates backward-compat shim (mcp_server.py) still exports all APIs
- Asserts package architecture: no circular imports, self-contained mcp/
- Module size regression guards prevent re-monolithization
- 16 pass locally, 10 skip (litellm dependency not installable)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(4.10): Address /8eyes + /collab review findings

Fixes from 4 reviewers (impl, sec, GPT-5.4, Opus 4.6):

- HIGH-1: Fix ToolRegistry API assertions (discover, select_and_inject, registry)
- HIGH-2: Use subprocess for circular import test (fresh process, not cached)
- HIGH-3: Exercise lazy proxy __getattr__ (force delegation to FastMCP)
- HIGH: Remove vacuous if-hasattr guards — assert tool structure directly
- MEDIUM-5: Tighten size guard thresholds (~10-14% headroom)
- MEDIUM-6: Add package-level MCP import test
- LOW-7: Replace deprecated asyncio.get_event_loop with asyncio.run()
- LOW: Assert files exist in size guards (deleted modules now fail)
- LOW: Strengthen error format assertions (verify isError, error_code, message)
- LOW: Add real assertion to cleanup delegation test

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: Brian Krafft <bkrafft@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people