feat(memory): ICM slice 2 — feedback record/search/stats

[NagyVikt]

Summary

ICM slice 2 (see docs/icm-integration-plan.md) — adds a cross-agent "AI predicted X, real answer was Y" feedback lane so a future agent can search prior corrections by topic before repeating a known mistake. Mirrors the observation surface: feedback_record (compressed write), feedback_search (compact FTS5 hits), feedback_stats (per-topic counts).

• Storage — migration 015 introduces feedback + a porter-unicode61 feedback_fts virtual table with the standard ai/ad/au triggers, plus indexes on topic and created_at. Importance is a four-level CHECK enum (critical|high|medium|low, default medium).
• Core — MemoryStore.recordFeedback routes prediction/correction/context through the same prepareMemoryText pipeline observations use, so the compression invariant holds at the write boundary. getFeedback honors settings.compression.expandForModel (and an explicit expand opt).
• MCP — three new tools wrap the facade with progressive-disclosure return shapes. docs/mcp.md documents the contract.

Verification

Run from this worktree:

• pnpm --filter @colony/storage typecheck — pass
• pnpm --filter @colony/storage test — pass (174/174, including new feedback.test.ts)
• pnpm --filter @colony/core typecheck — pass
• pnpm --filter @colony/core test — 254/255; the one failure (test/savings-reference.test.ts > does not attribute structured-output savings_report calls to the at-rest compression row) is pre-existing on main — reproduces with my changes stashed.
• pnpm --filter @colony/mcp-server typecheck — pass
• pnpm --filter @colony/mcp-server test — pass (302/302, including new feedback.test.ts and the updated server.test.ts tool-list expectation)
• pnpm exec biome check on touched files — clean; the lone diagnostic that remains is the pre-existing packages/storage/src/storage.ts::mcpMetricsMinTs formatter quirk that is unrelated to this change.

Test plan

• CI green across all packages
• Spot-check the new tools through the MCP inspector once merged
• Verify migration 015 applies forward-only against an existing dev DB

Follow-up (out of scope)

• Pre-tool-use hook that auto-surfaces prior corrections on inbound prompts. Tracking that as a separate PR so this slice can ship behind a manual query surface first.

References

• docs/icm-integration-plan.md — slice 2 spec (not authored in this PR; this implements it as written).