Audio Wave: fixed 721-frame subsegment grid + per-segment select/crop + notes box auto-fill

Pivot to the user's model: segments are a fixed grid of subsegment_frames frames
(default 721 @ 24fps = one LTX clip), not arbitrary clicks. New inputs:
subsegment_frames (grid size) and segment_select (0=all, N=output ONLY chunk N —
crops waveform_image, AUDIO, and summary so you can generate/skip one beat at a time).
_render gains window-crop + frame markers + per-segment time/frame labels. JS rewritten:
draws the fixed grid, auto-fills the notes box with one segN: line per chunk (type or
dblclick to note), click-to-seek, playhead + time readout. Workflows updated for the
new widgets.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

workflow/workflow_ltx_audio.json

@@ -113,7 +113,8 @@
       "widgets_values": [
         "audio.wav",
         24,
-        6,
+        721,
+        0,
         "",
         "[]"
       ]

workflow/workflow_ltx_audio_api.json

@@ -13,7 +13,8 @@
     "inputs": {
       "audio": "audio.wav",
       "fps": 24,
-      "max_segments": 6,
+      "subsegment_frames": 721,
+      "segment_select": 0,
       "notes": "",
       "segments_json": "[]"
     },