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>

backend/src/app.rs

@@ -185,6 +185,7 @@ async fn spawn_crawler_daemon(
             http: http.clone(),
             rate: Arc::clone(&rate),
             start_url: url.clone(),
+            manga_limit: cfg.manga_limit,
             download_allowlist: cfg.download_allowlist.clone(),
             max_image_bytes: cfg.max_image_bytes,
             tor: tor.as_ref().map(Arc::clone),
@@ -252,6 +253,7 @@ struct RealMetadataPass {
     http: reqwest::Client,
     rate: Arc<HostRateLimiters>,
     start_url: String,
+    manga_limit: usize,
     download_allowlist: DownloadAllowlist,
     max_image_bytes: usize,
     tor: Option<Arc<crate::crawler::tor::TorController>>,
@@ -267,7 +269,7 @@ impl MetadataPass for RealMetadataPass {
             &self.http,
             &self.rate,
             &self.start_url,
-            0,
+            self.manga_limit,
             false,
             &self.download_allowlist,
             self.max_image_bytes,