Adds technical design docs for the foundation of the doc-centric ingest pivot:
- 202 — Document lifecycle state machine
- 203 — Per (document, store) ingestion state
- 204 — Auto-detect Stale state via chunk content hash
- 205 — Audit trail for chunk edits (chunks → first-class entity)
- 206 — Migration of existing documents to the new model
Status: Accepted on all five. Each doc spells out the domain entities,
persistence schema, services orchestration, API contract, alternatives
considered, risks, and testing strategy. ADR placeholders called out
where load-bearing decisions warrant a follow-up document.
Refs #202#203#204#205#206
