fix(mcp): soul_forget always reports total_deleted=0

[IITI-tushar]

What does this PR do?

Fixes the soul_forget MCP tool always reporting total_deleted: 0 and tiers: {} regardless of how many memories were actually erased. The handler was reading result.get("total_deleted", 0) and result.get("tiers", {}) but MemoryManager.forget() returns keys total, episodic, semantic, and procedural. The CLI was corrected for this same mismatch in an earlier commit (see cli/main.py header line 19–20) but mcp/server.py was never updated.

Fixes #245

How to test

Reproduce before the fix:

1. Start the MCP server and birth a soul
2. Call soul_observe a few times with "Alice" content
3. Call soul_forget with query="Alice", confirm=True
4. Check response — total_deleted is always 0 before this fix

uv run pytest tests/test_mcp_sampling_engine.py tests/test_gdpr_deletion.py -v

Checklist

• Tests pass locally (uv run pytest tests/)
• Lint passes (uv run ruff check . && uv run ruff format --check .)
• No secrets or credentials in the diff
• PR title follows Conventional Commits (feat:, fix:, docs:, etc.)

[github-actions]

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