v0.24.0 - Correctness Release

Agent Memory Bridge 0.24.0 tightens the exact-identity, recall, and local
maintenance contracts without changing the 12-tool MCP surface.

What changed

• Schema version 4 adds exact_content_hash for exact memory identity.
  After the existing store/revise input trimming, it normalizes newline
  sequences only, preserves whitespace-sensitive content
  differences, and keeps legacy content_hash available.
• Semantic and hybrid recall use precomputed valid embeddings only. Recall does
  not backfill candidate embeddings or write during recall, and it reports
  degraded completeness when the derived index is cold, stale, or incomplete.
• Benchmark and proof paths explicitly warm the derived embedding index before
  semantic scoring.
• index-rebuild uses the same local service exclusion lock as other
  maintenance operations.
• docs/TRUST-BOUNDARY.md documents AMB's cooperative local trust boundary.

Validation snapshot

• pytest --collect-only -q tests: 560 tests collected
• Public MCP surface: exactly 12 tools
• Release, public-surface, onboarding, and targeted first-run tests are the
  release-surface gates for this patch.

Boundaries

This release does not add online restore, authenticated actors, namespace ACLs,
ANN retrieval, or multi-user infrastructure. FTS5 and embeddings remain derived
indexes; SQLite/WAL remains the durable authority.