Fix all cargo clippy warnings across the workspace

Removes genuinely dead code (unused import, no-op cast, an unused
PendingGrab accessor, and TmdbClient's TV-search methods now that TVDB
fully covers that path), tightens len()>0 checks to is_empty(), swaps
two fixed-size test vec!s for arrays, restructures a match to avoid an
unnecessary unwrap_err, fixes doc-comment list indentation, and hoists
a locked-connection call out of a match scrutinee. Struct fields/enum
variants that are still meaningful but not read by current callers
(TorrentInfo::save_path, GrabCycleStats::items_seen, X1337 fallback
route, BacklogCandidate::path) get #[allow(dead_code)] rather than
deletion, same for the two 8-argument functions (too_many_arguments).

breadarrd/src/main.rs

@@ -633,10 +633,11 @@ async fn background_loop(
                 // repaired (a rename or an in-place transcode) gets re-probed
                 // immediately rather than waiting for its own turn a full
                 // interval later.
-                match {
+                let probe_result = {
                     let conn = conn.lock().await;
                     importer::probe_library(&conn)
-                } {
+                };
+                match probe_result {
                     Ok(report) if report.probed > 0 || report.failed > 0 => {
                         info!(?report, "media probe sweep complete");
                     }