fix: add missing edit_song and edit_lyrics parameters to DiffRhythm workflows

Fix "edit song, edit lyrics, edit segments must be provided" error by adding
the two missing parameters to all three DiffRhythm workflow files:

- diffrhythm-random-generation-v1.json
- diffrhythm-reference-based-v1.json
- diffrhythm-full-length-t2m-v1.json

Added empty string parameters at positions 9 and 10 in widgets_values array:
- edit_song: "" (empty when edit=false)
- edit_lyrics: "" (empty when edit=false)

The DiffRhythmRun node requires 12 parameters total, not 10. These workflows
use edit=false (no editing), so the edit parameters should be empty strings.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

comfyui/workflows/text-to-music/diffrhythm-full-length-t2m-v1.json

@@ -30,6 +30,8 @@
         "quality",
         123,
         false,
+        "",
+        "",
         "[-1, 20], [60, -1]"
       ],
       "title": "DiffRhythm Full-Length Text-to-Music (4m45s)"

comfyui/workflows/text-to-music/diffrhythm-random-generation-v1.json

@@ -30,6 +30,8 @@
         "speed",
         -1,
         false,
+        "",
+        "",
         "[-1, 20], [60, -1]"
       ],
       "title": "DiffRhythm Random Generation (No Prompt)"

comfyui/workflows/text-to-music/diffrhythm-reference-based-v1.json

@@ -60,6 +60,8 @@
         "speed",
         456,
         false,
+        "",
+        "",
         "[-1, 20], [60, -1]"
       ],
       "title": "DiffRhythm Reference-Based Generation"