feat(crawler): honour CRAWLER_LIMIT in the in-process daemon (0.47.0)

The CLI binary already capped runs at CRAWLER_LIMIT mangas, but the
daemon's RealMetadataPass passed a hardcoded `0` (no cap) to
`pipeline::run_metadata_pass`, so the env var was silently ignored once
the daemon took over the metadata pass.

Adds `manga_limit` to `CrawlerConfig`, reads it from `CRAWLER_LIMIT`
(default 0 = no cap), and threads it through `RealMetadataPass::run`
so a daemon-driven sweep stops at the same boundary as a CLI run.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.env.example

@@ -74,6 +74,10 @@ CRAWLER_DOWNLOAD_ALLOWLIST=
 CRAWLER_ALLOW_ANY_HOST=false
 # Hard cap on a single image body. Default 32 MiB.
 CRAWLER_MAX_IMAGE_BYTES=33554432
+# Max manga detail fetches per metadata pass (both the in-process daemon
+# and the `bin/crawler` CLI). 0 means no cap — let the source walker run
+# to completion. Useful for capped test runs against a new source.
+CRAWLER_LIMIT=0
 # Path to a system Chromium binary. When set, the crawler skips the
 # bundled-fetcher download. Required on platforms without a usable
 # upstream Chromium build (notably Linux_arm64 / Raspberry Pi). On