Fix mixed content error for audio files behind HTTPS proxy

Add root_path setting to configure Gradio for HTTPS reverse proxy.
Set AUDIOCRAFT_ROOT_PATH env var to external URL (e.g., https://example.com).

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

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

config/settings.py

@@ -26,6 +26,7 @@ class Settings(BaseSettings):
     host: str = Field(default="0.0.0.0", description="Server bind host")
     gradio_port: int = Field(default=7860, description="Gradio UI port")
     api_port: int = Field(default=8000, description="FastAPI port")
+    root_path: Optional[str] = Field(default=None, description="External URL for reverse proxy (e.g., https://example.com)")
 
     # Paths
     data_dir: Path = Field(default=Path("./data"), description="Data directory")

main.py

@@ -152,12 +152,17 @@ def main():
     try:
         # Gradio 6.x: show_api replaced with footer_links
         footer = ["api", "gradio"] if settings.api_enabled else ["gradio"]
-        app.launch(
-            server_name=settings.host,
-            server_port=settings.gradio_port,
-            share=False,
-            footer_links=footer,
-        )
+        launch_kwargs = {
+            "server_name": settings.host,
+            "server_port": settings.gradio_port,
+            "share": False,
+            "footer_links": footer,
+        }
+        # Add root_path for HTTPS reverse proxy support
+        if settings.root_path:
+            launch_kwargs["root_path"] = settings.root_path
+            logger.info(f"Using root_path: {settings.root_path}")
+        app.launch(**launch_kwargs)
     except KeyboardInterrupt:
         logger.info("Shutting down...")
     finally: