Fix global legacy note search retrieval

[andrei-hasna]

Summary

• include active JSON-store notes in hybrid search as keyword-only legacy_item results with knowledge://item/<id> refs
• pass the active note store path through CLI/service search, context, and ask/build paths, including first-command global legacy migration from ~/.open-knowledge/db.json
• document the note-store vs SQLite source/wiki reindex boundary and add focused regression coverage

Validation

• bun test tests/search.test.ts tests/retrieval.test.ts tests/cli.test.ts --timeout 30000 passed: 45 tests, 460 assertions
• targeted TypeScript check for changed source/tests passed
• manual temp HOME smoke passed for current global notes and old ~/.open-knowledge/db.json first-command search migration
• bun test passed: 122 tests, 1477 assertions
• bun test tests/mcp.test.ts --timeout 30000 passed
• bun run build passed
• knowledge storage protect --scope project --json && knowledge storage validate --strict --scope project --json passed in the clean worktree

Notes

• knowledge reindex remains scoped to SQLite source/wiki chunks and vector rows; JSON notes are keyword-searchable/context-packable, not embedded by reindex.
• Repo-wide bunx tsc -p tsconfig.json --noEmit still fails on pre-existing unrelated test/rootDir/type drift; the targeted changed-file typecheck passes.
• Adversarial review found the first-command legacy migration blocker; it was fixed and the reviewer re-check reported no blocker remains.

[andrei-hasna]

Closing as superseded / already-fixed-on-main.

Every element of this PR is already present on main (via the reconcile of main to the published 0.2.x line) and has since been extended:

• src/search.ts: full legacy_item / active-JSON-note keyword search (readLegacyItems, selectLegacyItems, legacyItemResult, legacy_item SearchResultKind, kind-order) — present on main and further generalized into a shared selectItems that also serves the cloud api-mode item corpus (hybridSearchItems).
• src/service.ts: legacyStorePath plumbing for search/context/ask — present on main, extended with legacyStorePathForRead.
• src/retrieval.ts: authorityScore legacy_item 0.6 and RetrievalOptions legacyStorePath — present on main.
• README.md + docs/architecture/hybrid-semantic-search.md: the compatibility-JSON-note / knowledge://item/<id> / reindex-boundary docs — present on main.
• Tests: 'searches active legacy JSON notes as keyword results' (search), 'assembles context excerpts from legacy JSON notes' (retrieval), and 'global notes added through CLI are searchable and available as context' (cli) — all already on main.

Additionally, main deliberately reverses this PR's migrate-on-read behavior: main carries 'global search reads the old legacy note store without migration' and 'global list does not migrate legacy .open-knowledge data on read', and scopes ensureStore to ask/build (not search) and only outside api-mode. Rebasing this PR conflicts on cli.ts/search.ts/service.ts/cli.test.ts and would re-introduce the superseded migrate-on-read path. Nothing unique remains to salvage. Closing.