feat: drop rms_display from /api/analyze

The UI no longer draws waveforms, so the server stops computing and
sending the ~800-point RMS preview; the payload is now just sections,
duration, window. Old analysis caches stay valid: rms/rms_display are
popped when serving a cache hit (same pattern as the earlier full-RMS
removal), so no DETECTOR_VERSION bump.

Verified: 63 tests pass; endpoint smoke test (fresh + cached analyze)
confirms no RMS keys and correct section detection.

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

web.py

@@ -402,16 +402,9 @@ def _package_result(rms_values: list, framerate: int, n_frames: int,
     window_dur = window_samples / framerate
     duration   = n_frames / framerate
 
-    if len(rms_values) > 800:
-        step = len(rms_values) / 800
-        rms_display = [rms_values[int(i * step)] for i in range(800)]
-    else:
-        rms_display = rms_values
-
-    # Note: the full per-window RMS list is deliberately NOT returned — the UI
-    # only renders rms_display (~800 points), and the full list is ~45x larger.
+    # Note: no RMS data is returned — the UI is screen-reader oriented and
+    # draws no waveform, so sections + duration is all it needs.
     return {
-        'rms_display': rms_display,
         'sections':    _loud_sections(rms_values, window_dur, duration, margin_db, min_gap, min_duration),
         'duration':    round(duration, 2),
         'window':      round(window_dur, 4),
@@ -690,7 +683,9 @@ class _Handler(BaseHTTPRequestHandler):
                     and cached.get('margin') == margin and cached.get('min_gap') == min_gap
                     and cached.get('min_duration') == min_duration):
                 payload = dict(cached['result'])
-                payload.pop('rms', None)  # caches written before the full-RMS field was dropped
+                # strip fields that older cache versions embedded
+                payload.pop('rms', None)          # full per-window RMS list
+                payload.pop('rms_display', None)  # ~800-point waveform preview
                 payload['cached'] = True
                 self._send(200, json.dumps(payload).encode('utf-8'), 'application/json')
                 return