feat: Qobuz pacing budget gate (human-like volume + cadence)

Avoid re-triggering a USER_BLOCKED account by capping Qobuz to a human-looking
volume and cadence. A per-album gate (worker/lyra_worker/qobuz_gate.py) allows
Qobuz only within active hours, under today's cap (a warm-up ramp of a steady
cap), and past a randomized spacing since the last Qobuz download; the gap spreads
the day's budget across active hours with jitter. When the gate is closed the
pipeline drops Qobuz candidates so the job falls through to another source (and
monitored albums upgrade to Qobuz later); a Qobuz-only setup is never gated.
Config keys read live each loop; counters reset at the day boundary via the DB
clock. Tunable in Settings -> Qobuz -> Pacing (new /api/qobuz/pacing route).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/lyra_worker/pipeline.py

@@ -1,4 +1,5 @@
 import os
+import random
 import shutil
 import threading
 import time
@@ -11,6 +12,7 @@ import psycopg
 from lyra_worker.adapters.base import SourceAdapter
 from lyra_worker.confidence import score_confidence
 from lyra_worker.library import album_dir, import_album, list_audio_files, staging_dir
+from lyra_worker.qobuz_gate import gate_open, record_download
 from lyra_worker.quality import quality_class
 from lyra_worker.ranker import rank_candidates
 from lyra_worker.types import Candidate, MBTarget
@@ -365,6 +367,13 @@ def run_pipeline(
             found.append(replace(c, source_tier=adapter.tier, confidence=score_confidence(target, c)))
     _persist_candidates(conn, job_id, found)
 
+    # Qobuz pacing: when the budget gate is closed (off-hours / daily cap / spacing), drop Qobuz
+    # candidates so the job falls through to another source and Qobuz stays under the radar — UNLESS
+    # Qobuz is the only option (nothing to fall through to, so don't strand the album).
+    if any(c.source == "qobuz" for c in found) and any(c.source != "qobuz" for c in found):
+        if not gate_open(conn):
+            found = [c for c in found if c.source != "qobuz"]
+
     # 3. rank
     _set_state(conn, job_id, "matched", "rank")
     ranked = rank_candidates(target, found, min_confidence)
@@ -415,6 +424,12 @@ def run_pipeline(
             _fail(conn, job_id, last_problem or "all downloads failed")
             return
         _set_download_progress(conn, job_id, 1.0)  # download done — UI shows 100% into Finishing
+        if winner.source == "qobuz":
+            # Count this Qobuz download against today's budget and set the next randomized spacing.
+            try:
+                record_download(conn, random.random())
+            except Exception as e:  # pacing bookkeeping must never fail a good download
+                print(f"pipeline: qobuz pacing record failed for job {job_id}: {e}", flush=True)
 
         # 5. promote + tag the verified winner
         _set_state(conn, job_id, "tagging", "tag")