feat(career): gigs backend — propose a setlist, log the completed set (#954)

* feat(career): gigs backend — propose a setlist, log the completed set

Career v3, WS3 (backend half). A gig is career's verb:

- POST /gigs/propose {instrument, genre, size}: setlist from the
  passport's own stubs — qualifying songs (per the genre's badge bar,
  family-aware) shuffled for a free re-roll, topped with the
  highest-accuracy near-bar songs as stakes, and filled from UNPLAYED
  genre songs when the passport is young (the first gig is how stubs
  start). Names the highest venue the current stars can book.
- POST /gigs: logs a COMPLETED set only (abandoned sets never log — no
  fail state). Per-song accuracy = MAX(last_accuracy) from song_stats,
  freshly written by the set's own plays; encore = avg ≥ the data-driven
  bar (passports.json gig.encore_accuracy, 0.75). Appends to the career
  state file (same atomic _save_json pattern).
- Passports view: per-passport gigs (newest first, capped 20) and
  per-instrument gig_count — the profile wall's gig line lights up.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(career): gig backfill offsets by qualifying taken, not picks length

CodeRabbit on #954: after the stakes loop appends near-bar songs,
qualifying[len(picks):] overshoots and skips eligible qualifying songs
— a stocked passport could still get a short set.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

tests/plugins/career/conftest.py

@@ -26,7 +26,7 @@ class FakeMetaDb:
         self.conn.execute(
             """CREATE TABLE song_stats (
                    filename TEXT, arrangement TEXT, best_accuracy REAL,
-                   last_played_at TEXT,
+                   last_accuracy REAL, last_played_at TEXT,
                    seconds_total REAL NOT NULL DEFAULT 0
                )"""
         )
@@ -38,10 +38,12 @@ class FakeMetaDb:
         )
 
     def add(self, filename, arrangement, best_accuracy, in_library=True,
-            genre="", arrangements=None, last_played_at=None, seconds_total=0):
-        self.conn.execute("INSERT INTO song_stats VALUES (?, ?, ?, ?, ?)",
-                          (filename, arrangement, best_accuracy, last_played_at,
-                           seconds_total))
+            genre="", arrangements=None, last_played_at=None, seconds_total=0,
+            last_accuracy=None):
+        self.conn.execute("INSERT INTO song_stats VALUES (?, ?, ?, ?, ?, ?)",
+                          (filename, arrangement, best_accuracy,
+                           last_accuracy if last_accuracy is not None else best_accuracy,
+                           last_played_at, seconds_total))
         if in_library:
             self.conn.execute(
                 "INSERT INTO songs SELECT ?, ?, ?, ?, ? WHERE NOT EXISTS "