Implements the missing pieces of the MemPalace epic (#367):
- sovereign_store.py: Self-contained memory store replacing the third-party
mempalace CLI and its ONNX dependency. Uses:
* SQLite + FTS5 for keyword search (porter stemmer, unicode61)
* HRR phase vectors (SHA-256 deterministic, numpy optional) for semantic similarity
* Reciprocal Rank Fusion to merge keyword and semantic rankings
* Trust scoring with boost/decay lifecycle
* Room-based organization matching the existing PalaceRoom model
- promotion.py (MP-4, #371): Quality-gated scratchpad-to-palace promotion.
Four heuristic gates, no LLM call:
1. Length gate (min 5 words, max 500)
2. Structure gate (rejects fragments and pure code)
3. Duplicate gate (FTS5 + Jaccard overlap detection)
4. Staleness gate (7-day threshold for old notes)
Includes force override, batch promotion, and audit logging.
- 21 unit tests covering HRR vectors, store operations, search,
trust lifecycle, and all promotion gates.
Zero external dependencies. Zero API calls. Zero cloud.
Refs: #367#370#371
