refactor: migrate thread/async/queue/scheduler infra to mytheclipse

- bootstrap: TracingLayer from mytheclipse-tracing (composed with scraper
  env filter), RuntimeConfig::auto() thread logging, init job queue + cron.
- proxy_fetch: leader task via ::mytheclipse::spawn_io, gzip decompression
  offloaded to ::mytheclipse::compute (sized rayon pool, panic-isolated),
  bounded by new async fetch limiter (tokio Semaphore bridge).
- queue: new infrastructure/queue module over mytheclipse-queue
  (InMemoryQueue + WorkerPool + BackpressureEnforcer) for repair jobs.
- scheduler: new infrastructure/scheduler.rs using mytheclipse::cron for
  the daily 02:00 UTC image-cache cleanup.
- deps: add mytheclipse-queue + mytheclipse-tracing path deps; mytheclipse
  -> full feature; rayon 1.12; keep path deps for unpublished crates.
- tests: infra_round2 runtime smoke tests (compute panic isolation,
  spawn_io, backpressure admission, cron parse, queue roundtrip).
- Fix: local cache::mytheclipse bridge module shadowed the mytheclipse
  crate name; use leading :: at spawn_io/compute call sites.

src/infrastructure/scheduler.rs

@@ -0,0 +1,27 @@
+//! Scheduled maintenance jobs — driven by `mytheclipse::cron`.
+//!
+//! The scraper runs a daily 02:00 UTC cache-cleanup job that enqueues
+//! image-cache repair work onto the application job queue. The cron driver
+//! comes from the mytheclipse core crate (`schedule` + `CronSchedule`); the
+//! actual per-key repair work is queued through `mytheclipse-queue`.
+
+use mytheclipse::cron::schedule;
+
+/// Starts the daily maintenance jobs on a background task.
+///
+/// Returns the [`mytheclipse::cron::CronJob`] handle so the caller can keep
+/// it alive (and abort on shutdown if needed).
+pub fn start_scheduler() -> Result<mytheclipse::cron::CronJob, mytheclipse::cron::CronError> {
+    // 02:00 UTC every day — "minute hour dom month dow"
+    let job = schedule("0 2 * * *", || async {
+        tracing::info!("[scheduler] running daily cache cleanup");
+        // Enqueue a sentinel repair job — the queue worker handles the actual
+        // sweep. In a follow-up round this enumerates stale cache entries and
+        // enqueues one job per URL.
+        let _ =
+            crate::infrastructure::queue::enqueue_cache_repair("__daily_sweep__".to_string()).await;
+        tracing::info!("[scheduler] daily cache cleanup enqueued");
+    })?;
+    tracing::info!("[scheduler] daily cache cleanup scheduled at 02:00 UTC");
+    Ok(job)
+}