refactor: rename backend/frontend dirs and remove NovelWriter submodule

- Rename qwen3-tts-backend → canto-backend
- Rename qwen3-tts-frontend → canto-frontend
- Remove NovelWriter embedded repo

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

canto-backend/indextts/s2mel/dac/__main__.py

@@ -0,0 +1,36 @@
+import sys
+
+import argbind
+
+from dac.utils import download
+from dac.utils.decode import decode
+from dac.utils.encode import encode
+
+STAGES = ["encode", "decode", "download"]
+
+
+def run(stage: str):
+    """Run stages.
+
+    Parameters
+    ----------
+    stage : str
+        Stage to run
+    """
+    if stage not in STAGES:
+        raise ValueError(f"Unknown command: {stage}. Allowed commands are {STAGES}")
+    stage_fn = globals()[stage]
+
+    if stage == "download":
+        stage_fn()
+        return
+
+    stage_fn()
+
+
+if __name__ == "__main__":
+    group = sys.argv.pop(1)
+    args = argbind.parse_args(group=group)
+
+    with argbind.scope(args):
+        run(group)