Add LTX audio workflow + Text (Prompt) node

New workflow/workflow_ltx_audio_api.json: Audio Wave + Segments + LoadImage (subject)
+ Text (Prompt) holding the LTX audio system prompt -> Judge in chat mode
(json_output, model 3.5-9b) -> LTX beats JSON on the analysis output. Added a tiny
CalibratorText node ('Text (Prompt)', STRING source) needed to feed the judge's
forceInput system_prompt/user_prompt/axes sockets. README points to the workflow.

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

README.md

@@ -101,6 +101,13 @@ seg1: slow dreamy intro          # by segment number (also "1:" or "S1:")
 cinematic, moody grade           # no prefix = global (applies throughout)
 ```
 
+**Ready-made workflow:** `workflow/workflow_ltx_audio_api.json` wires it all up —
+`Audio Wave + Segments` + `LoadImage` (subject) + `Text (Prompt)` (the LTX system prompt
+from `prompts/ltx_audio_relay_system_prompt.txt`) → the judge in chat mode
+(`json_output=true`, model `3.5-9b`). Load it, upload your audio + set your subject image,
+and the judge's `analysis` output is the LTX beats JSON. (`Text (Prompt)` is a small STRING
+node this pack adds to feed the judge's `system_prompt`/`user_prompt`/`axes` sockets.)
+
 ### Interactive: `Audio Wave + Segments`
 
 Same outputs, but with an in-node waveform widget: **upload** an audio clip, **play** it,