Add keyword recall for experiences

[hijzy]

Summary

• Render recalled experiences in their own top-level prompt section beside memories, skills, and environment knowledge.
• Add policies FTS/pattern search so feedback-derived experiences can be recalled through keyword channels as well as vectors.
• Cover experience section rendering, degraded-embedding keyword recall, and policies keyword repository search.

Test plan

• npm test -- tests/unit/retrieval/injector.test.ts tests/unit/retrieval/integration.test.ts tests/unit/storage/repos.test.ts
• npm run lint