Refactor TTS provider management and enhance documentation

- Renamed `bundled-mlx` to `apple-mlx` for clarity in provider types.
- Updated the ProviderSettings component to reflect the new provider naming.
- Improved logging for provider startup and error handling in the backend.
- Added scripts for building and installing PyTorch CPU and CUDA providers locally.
- Enhanced the documentation to include details on TTS provider architecture and development setup.

scripts/build-providers-local.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+"""
+Build and install all TTS providers locally for development.
+"""
+
+import subprocess
+import sys
+from pathlib import Path
+
+
+def main():
+    """Build and install all providers."""
+    project_root = Path(__file__).parent.parent
+    providers_dir = project_root / "providers"
+
+    providers = ["pytorch-cpu", "pytorch-cuda"]
+
+    for provider in providers:
+        provider_path = providers_dir / provider
+        script_path = provider_path / "build_and_install.py"
+
+        if not script_path.exists():
+            print(f"⚠ Skipping {provider}: build_and_install.py not found")
+            continue
+
+        print(f"\n{'=' * 60}")
+        print(f"Building and installing {provider}...")
+        print(f"{'=' * 60}\n")
+
+        try:
+            subprocess.run(
+                [sys.executable, str(script_path)],
+                cwd=provider_path,
+                check=True,
+            )
+        except subprocess.CalledProcessError as e:
+            print(f"✗ Failed to build {provider}: {e}")
+            sys.exit(1)
+
+    print(f"\n{'=' * 60}")
+    print("✓ All providers built and installed successfully!")
+    print(f"{'=' * 60}\n")
+
+
+if __name__ == "__main__":
+    main()