feat: crawler manga-list & metadata sync with cover download (0.23.0)

- TargetSource: first concrete impl of the Source trait, modeled on
  the old Puppeteer crawler's selectors (+ status normalization,
  tag-count stripping, chapter list)
- DiscoverMode::Backfill walks pagination last->1, reverse within each
  page (oldest-first); Incremental walks forward
- RateLimiter (tokio-time aware) plumbed through FetchContext so the
  pagination walk honors the same per-host budget as the outer loop
- repo::crawler: ensure_source, upsert_manga_from_source (returns
  New/Updated/Unchanged + current cover_image_path for backfill
  decisions), sync_manga_chapters, mark_dropped_mangas — all
  transactional, with case-insensitive lookups and source-insertable
  genres
- Cover image download via reqwest+infer; stored under
  mangas/{id}/cover.{ext} via the Storage trait
- Single CRAWLER_PROXY env wires both Chromium (--proxy-server) and
  reqwest::Proxy::all (HTTP/HTTPS/SOCKS5)
- Crawler binary: positional start URL or $CRAWLER_START_URL,
  $CRAWLER_LIMIT (cap fetches + skip drop pass on partial runs),
  $CRAWLER_SKIP_CHAPTERS (disable selector AND sync), $CRAWLER_RATE_MS
- Silences chromiumoxide 0.7's known CDP deserialize log spam via
  default tracing filter + CdpError::Serde downgrade
- 9 sqlx integration tests + 11 selector/rate-limit unit tests

backend/Cargo.toml

@@ -1,7 +1,8 @@
 [package]
 name = "mangalord"
-version = "0.22.0"
+version = "0.23.0"
 edition = "2021"
+default-run = "mangalord"
 
 [lib]
 path = "src/lib.rs"
@@ -44,6 +45,7 @@ futures-util = "0.3"
 bytes = "1"
 chromiumoxide = { version = "0.7", features = ["tokio-runtime", "_fetcher-rusttls-tokio"], default-features = false }
 scraper = "0.20"
+reqwest = { version = "0.12", default-features = false, features = ["rustls-tls", "socks"] }
 
 [dev-dependencies]
 tempfile = "3"
@@ -51,3 +53,4 @@ tower = { version = "0.5", features = ["util"] }
 http-body-util = "0.1"
 mime = "0.3"
 futures-util = "0.3"
+tokio = { version = "1", features = ["test-util"] }