josh
13139547f7
7 commits across 3 TDD tasks (RED + GREEN per task) + .gitkeep cleanup; 36 Vitest tests across 7 test files green; npm run build clean under TypeScript strict; all 6 CORE requirements (CORE-04 through CORE-09) covered by at least one assertion. Key structural decision documented in SUMMARY: SaveDB is a single common-contract interface, not a union of IDBPDatabase | LocalStorageDBAdapter. The union shape failed TypeScript-strict at the build gate; the interface refactor isolates the type-system cast to one location at openSaveDB().