Adds a scraping_tasks PocketBase collection with fields for kind, status,
progress counters, timestamps, and error info. Exposes CreateScrapeTask,
UpdateScrapeTask, and ListScrapeTasks on the Store interface with
implementations in HybridStore and PocketBaseStore.
- Inject *slog.Logger into HybridStore, PocketBaseStore, and pbClient
- Fix credential defaults in main.go (changeme123 / admin) to match docker-compose
- listOne/listAll/upsert/deleteWhere now return errors on non-2xx HTTP status
- WriteChapter: log warn instead of discarding UpsertChapterIdx error
- MetadataMtime, GetAudioCache, GetProgress: log warn on PocketBase failures
- EnsureCollections: log info/debug/warn per outcome instead of _ = err
- CountChapterIdx: log warn on failure instead of silently returning 0
- server: log warn when SetAudioCache fails after audio generation
- NewHybridStore: add explicit Ping() before EnsureCollections for fast-fail on bad credentials
- Replace SetRanking/GetRanking/SetRankingPageHTML/GetRankingPageHTML blob methods
with WriteRankingItem/ReadRankingItems/RankingFreshEnough per-item operations
- Add 24h staleness gate in ScrapeRanking to skip re-scraping fresh data
- Add GET /api/ranking endpoint returning []RankingItem sorted by rank
- Remove RankingPageCacher interface and rankingCacheAdapter adapter
- Update integration tests to use new per-item upsert semantics
- Include e2e test suite (scraper/internal/e2e/)
