fix(player): redesign cleanup pass — sleeve, tonearm, AGC, dead code

Production-readiness pass before merging the Studio Reference redesign
to master.

Audio (backend):
- Reset AGC `_spectrum_ref` envelope on `start()` so a long silent gap
  between sessions doesn't make the first new transients clip at the
  ceiling. Annotated the trade-off (loud transient lifts reference for
  a few seconds afterwards — the price of real loudness).
- Add `tests/test_audio_analyzer.py` with 10 cases: bin-edge layout,
  AGC attack/release asymmetry, lifecycle reset. Skips numpy-dependent
  cases when numpy isn't installed; CI has it.

Vinyl mode dead code removed:
- The toggle button was dropped during the sleeve refactor but the JS
  state, 2 s `setInterval`, `beforeunload` handler, and `applyVinylMode`
  call (commented out in app.js) all stayed. Now properly excised from
  player.js + app.js + window.* exports.
- Stripped the matching `.album-art-container.vinyl*` CSS block and its
  `vinylSpin` keyframes (~95 LoC).

Sleeve + tonearm fixes:
- Removed the duplicate `.now-playing .vinyl-stage` / `.vinyl-label` /
  `.tonearm` block that was overriding the new `.vinyl-stage` rules by
  source order — the uncommitted tonearm geometry never took effect
  because the stale clone won the cascade.
- Tightened tonearm to 36% × 36% at right:-6%, top:26% so the SVG
  bounding box stays right of the sleeve (sleeve right edge ~68%).
  Needle now lands on the visible disc grooves at both rest and
  playing rotations and never overlaps the cover.
- Removed sleeve `transform: rotate(-2.5deg)` + the matching mobile
  `-1.8deg` override; sleeve now sits flat and squared-off.
- Removed the 1px inset hairline on the sleeve and the 1px outline +
  inset highlight on the album art — cleaner, no semitransparent
  border noise.
- Album art inset 5% to expose a cardstock margin around the print
  (using explicit width/height — `inset` shorthand triggered the CSS
  replaced-element rule that uses the image's intrinsic size and blew
  out the grid track).

Mobile + misc:
- Removed mobile tonearm overrides at 720px and 420px — they were
  calibrated for the pre-sleeve geometry and put the needle back over
  the cover on phones; desktop geometry is proportional and works.
- Added `<meta name="mobile-web-app-capable">` alongside the legacy
  Apple variant to silence the deprecation warning in Chromium.
- Replaced the "PRIMARY" badge on display cards with a copper star
  icon (translation key still drives title + aria-label).
- `.gitattributes` with `* text=auto eol=lf` so Windows checkouts stop
  nagging "LF will be replaced by CRLF".

Annotations:
- "REF · 24" record-label catalogue mark marked as intentional non-i18n
  decoration in index.html.

CI: ruff clean, pytest 7 passed + 3 numpy-skipped (all 10 run on CI).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

media_server/static/index.html

@@ -6,6 +6,7 @@
     <title>Media Server</title>
     <meta name="description" content="Remote media player control and file browser">
     <meta name="theme-color" content="#121212">
+    <meta name="mobile-web-app-capable" content="yes">
     <meta name="apple-mobile-web-app-capable" content="yes">
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
     <meta name="apple-mobile-web-app-title" content="Media Server">
@@ -159,12 +160,21 @@
         <div class="player-container" data-tab-content="player" role="tabpanel" id="panel-player">
             <section class="now-playing player-layout">
 
-                <!-- Vinyl stage with album art as label, plus tonearm -->
+                <!-- Vinyl stage: cardstock sleeve + disc peeking out, plus tonearm -->
                 <div class="vinyl-stage album-art-container">
-                    <div class="vinyl">
-                        <div class="vinyl-label">
-                            <img id="album-art-glow" class="album-art-glow" src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 300 300'%3E%3Crect fill='%23282828' width='300' height='300'/%3E%3C/svg%3E" alt="" aria-hidden="true">
-                            <img id="album-art" src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 300 300'%3E%3Crect fill='%23282828' width='300' height='300'/%3E%3Cpath fill='%236a6a6a' d='M150 80c-38.66 0-70 31.34-70 70s31.34 70 70 70 70-31.34 70-70-31.34-70-70-70zm0 20c27.614 0 50 22.386 50 50s-22.386 50-50 50-50-22.386-50-50 22.386-50 50-50zm0 30a20 20 0 100 40 20 20 0 000-40z'/%3E%3C/svg%3E" alt="Album Art">
+                    <img id="album-art-glow" class="album-art-glow" src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 300 300'%3E%3Crect fill='%23282828' width='300' height='300'/%3E%3C/svg%3E" alt="" aria-hidden="true">
+                    <div class="sleeve">
+                        <img id="album-art" src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 300 300'%3E%3Crect fill='%23282828' width='300' height='300'/%3E%3Cpath fill='%236a6a6a' d='M150 80c-38.66 0-70 31.34-70 70s31.34 70 70 70 70-31.34 70-70-31.34-70-70-70zm0 20c27.614 0 50 22.386 50 50s-22.386 50-50 50-50-22.386-50-50 22.386-50 50-50zm0 30a20 20 0 100 40 20 20 0 000-40z'/%3E%3C/svg%3E" alt="Album Art">
+                        <div class="sleeve-grain" aria-hidden="true"></div>
+                        <div class="sleeve-corner" aria-hidden="true"></div>
+                    </div>
+                    <div class="vinyl-wrap">
+                        <div class="vinyl">
+                            <div class="vinyl-label">
+                                <!-- Stylised record-label catalogue mark, not user-facing
+                                     copy — intentionally not in the i18n bundle. -->
+                                <span class="vinyl-label-text">REF · 24</span>
+                            </div>
                         </div>
                     </div>
                     <svg class="tonearm" viewBox="0 0 200 200" aria-hidden="true">