feat(career): hours-per-genre odometer — honest wall-clock play time

Career v2, WS2. Nothing measured play time before (the achievements
plugin's final-position shortcut double-counts loops and mis-reads
seeks). Now:

- stats-recorder.js accrues WALL-CLOCK seconds across song:play/resume ↔
  pause/stop/ended spans (single spans clamp at 2h against suspend
  inflation) and piggybacks them as `seconds` on the POSTs it already
  sends; failed POSTs restore the accumulator; a session reset flushes
  first so time can't re-attribute to the next song/arrangement.
- POST /api/stats accepts optional `seconds` (finite, 0 < s ≤ 6h) on the
  scored and position branches, plus a new seconds-only branch for
  unscored plays that ran to the natural end — banks time WITHOUT
  touching the resume position (song:ended must not overwrite Continue)
  and still counts as playing today for the streak.
- song_stats gains additive idempotent `seconds_total`; record_session/
  touch_position accrue, new add_play_seconds() for the seconds-only
  path; the legacy-encoding stats merge sums seconds across duplicates.
- Passports surface it: "14.2 h in Blues" under the badge stamp and on
  the shelf cover sub-line — a true fact that only grows, never a
  target or a meter (Stage 5 post-cap, per the career design).

Tests: seconds accrual/validation/seconds-only branch (stats API),
per-instrument-and-genre summing (career), fmtHours formatting (vm).
Full suites: pytest 2480, JS 1165.

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

tests/plugins/career/test_passports.py

@@ -143,3 +143,15 @@ def test_drill_state_validation(client):
     huge = {"byNode": {"pad": "x" * (300 * 1024)}}
     assert client.post("/api/plugins/career/drill-state",
                        json=huge).status_code == 413
+
+
+def test_hours_odometer_sums_seconds_per_instrument_and_genre(client, meta_db):
+    both = [{"type": "lead", "name": "Lead"}, {"type": "bass", "name": "Bass"}]
+    # Two lead arrangements' time sums; the bass row stays on the bass passport.
+    meta_db.add("a.feedpak", 0, 0.8, genre="Blues", arrangements=both, seconds_total=600)
+    meta_db.add("b.feedpak", 0, 0.8, genre="Blues", arrangements=both, seconds_total=300)
+    meta_db.add("b.feedpak", 1, 0.9, genre="Blues", arrangements=both, seconds_total=1200)
+    _open(client, "guitar")
+    _open(client, "bass")
+    assert _passport(client, "guitar")["seconds_total"] == 900
+    assert _passport(client, "bass")["seconds_total"] == 1200