Persist + sync review logs (streak foundation)

[bootuz]

Summary

Sub-project 1 of 2 for the streak system. Persists every FSRS review as an immutable ReviewLog and syncs them to Firestore — fixing the gap where StudyViewModel.onRate computed ScheduleResult.log and discarded it. This gives the app a real per-review history (the data the streak — and later stats/heatmap — will derive from) plus a synced backup.

• Room: new immutable review_logs table + ReviewLogDao, AzriDatabase → v2 with an additive Migration(1,2) (CREATE TABLE matched byte-for-byte to Room's generated schema — verified against AzriDatabase_Impl.kt; no destructive wipe).
• Domain/repo: ReviewLog/ReviewLogDto gain id/cardId (defaulted — SchedulingService.schedule() stays pure); ReviewLogRepository.append() assigns a UUID + marks the row dirty.
• Write path: onRate now persists result.log (best-effort, fire-and-forget — never blocks rating).
• Sync: flat users/{uid}/reviewLogs/{logId} (each carrying cardId), append-only union — push dirty logs then clear; pull inserts only ids not already local (@Insert(OnConflictStrategy.IGNORE)), no last-write-wins since logs are immutable. The existing card/deck/folder sync is untouched.

Out of scope (sub-project 2): the streak itself (will consume ReviewLogRepository.observeLogs()); the iOS cards/{id}/history subcollection; log pruning; backfilling history for already-rated cards.

Test plan

• ReviewLogDtoTest, ReviewLogMapperTest (incl. null state/due) — id/cardId/all fields round-trip domain ↔ entity ↔ DTO.
• ReviewLogRepositoryTest — append assigns the injected id + cardId + dirty.
• StudyViewModelTest — rating appends exactly one log with the right cardId/rating.
• SyncManagerTest — dirty logs pushed then cleared; pull unions remote logs and SyncManager's own filter skips an already-present id (asserted via inserted-batch capture, not just DAO dedup).
• Full unit-test suite green; instrumented sources compile; :app:assembleDebug BUILD SUCCESSFUL.
• Manual smoke (pending emulator — verifies the live Room migration): install over an existing v1 build (no uninstall) → opens without a schema crash, data preserved; rate cards → review_logs fills; signed-in sync → users/{uid}/reviewLogs populates and a repeat sync adds no duplicates.

🤖 Generated with Claude Code