Add SxCP Audio Prompt Guide node (audio -> waveform image + timing summary)

New node for audio-guided video prompts (LTX): takes a ComfyUI AUDIO clip + free-text
motion notes and outputs (1) a rendered energy-envelope IMAGE with beat/segment markers
so the vision model can see the audio shape, and (2) an audio_summary STRING with
duration, tempo/beats (librosa optional), per-segment energy + 8n+1-snapped frame counts
+ stage hints + the notes. Wire waveform_image -> Judge.reference_image and audio_summary
-> Judge.user_prompt (chat mode, json_output) for beat-aligned LTX JSON. librosa optional
(energy envelope + segments work without it). Registered in __init__; README workflow added.

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

README.md

@@ -62,6 +62,30 @@ Set **`json_output=true`** for JSON-producing system prompts — it extracts the
 from the reply (stripping any reasoning, prose, or ```fences) and returns it clean and
 re-serialized (falls back to raw text if none parses). Works even with `enable_thinking` on.
 
+## Audio-guided prompts (`SxCP Audio Prompt Guide`)
+
+For audio-driven video (e.g. LTX prompt-relay timed to music), the `AudioPromptGuide` node
+turns an audio clip + your free-text motion **notes** into inputs the vision model can use:
+
+- **`waveform_image`** (IMAGE) — the energy envelope with beat markers + segment boundaries,
+  so the model can *see* the audio's shape.
+- **`audio_summary`** (STRING) — duration, tempo/beats (if `librosa` is installed), a
+  per-segment energy breakdown with **8n+1-snapped frame counts** and stage hints
+  (establish→build→peak→settle), plus your notes.
+
+Wire it into the judge node in **chat mode**:
+
+```
+LoadAudio ─► SxCP Audio Prompt Guide ─┬─ waveform_image ─► Judge.reference_image
+   (your notes: "fast on the drop")   └─ audio_summary  ─► Judge.user_prompt
+   (LTX system prompt text node) ─────────────────────────► Judge.system_prompt
+                                        Judge (mode=chat, json_output=true) ─► LTX beats JSON
+```
+
+The model then gets the audio's timing/energy + your motion notes and writes beat durations,
+camera moves, and deltas that escalate with the music. `librosa` is optional (BPM/beats);
+without it you still get the energy envelope + segments.
+
 ## Performance / speed
 
 This node runs models through **transformers `.generate()`** — the simplest path, but the