Add MCP-style API server (OpenAPI) alongside WebUI

- New mcp_server.py: FastAPI app for LLMs to upload audio and get transcript JSON.
- Added process_mcp_transcribe_task Celery task.
- Updated __main__.py: WebUI always runs; MCP server runs in parallel when MCP_SERVER_ENABLED=true.

scraibe/__main__.py

@@ -3,10 +3,40 @@ Entrypoint for running ScrAIbe as a module:
 
     python -m scraibe
 
-Always launches the Web GUI (Gradio), never the CLI.
+Always launches the Web GUI (Gradio).
+Optionally launches an MCP-style API server in parallel.
 """
 
+import os
+import threading
+
 from .webui import create_app
 
+
+def _run_mcp_server():
+    """
+    Run MCP server in a separate thread.
+    """
+    import uvicorn
+    from . import mcp_server
+
+    host = os.getenv("MCP_SERVER_HOST", "0.0.0.0")
+    port = int(os.getenv("MCP_SERVER_PORT", "8000"))
+
+    uvicorn.run(
+        mcp_server.app,
+        host=host,
+        port=port,
+        log_level="info",
+    )
+
+
 if __name__ == "__main__":
+    # Optionally start MCP server in background
+    mcp_enabled = os.getenv("MCP_SERVER_ENABLED", "false").strip().lower() in ("true", "1", "yes")
+    if mcp_enabled:
+        t = threading.Thread(target=_run_mcp_server, daemon=True)
+        t.start()
+
+    # Always start WebUI (Gradio)
     create_app()