M6: EventSourcedDocumentStorage with projections, update operators, queries, planner, unique indexes, catch-up

Writes append resolved deltas with optimistic concurrency and self-heal lagging
projections. Reads hit projections only. Index-backed find is property-tested
against unindexed find.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017Qxbkp4tA7G5SCWjzWuxmE

src/index.ts

@@ -4,3 +4,4 @@ export * from './core/encoding.js'
 export * from './kv/index.js'
 export * from './types/schema.js'
 export * from './events/index.js'
+export * from './documents/index.js'