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.

providers/pytorch-cpu/build_and_install.py

@@ -0,0 +1,57 @@
+"""
+Build PyTorch CPU provider and install to local provider directory.
+"""
+
+import platform
+import shutil
+from pathlib import Path
+
+from build import build_provider
+
+
+def get_providers_dir() -> Path:
+    """Get the directory where providers are stored."""
+    system = platform.system()
+
+    if system == "Windows":
+        appdata = Path.home() / "AppData" / "Roaming"
+    elif system == "Darwin":
+        appdata = Path.home() / "Library" / "Application Support"
+    else:  # Linux
+        appdata = Path.home() / ".local" / "share"
+
+    providers_dir = appdata / "voicebox" / "providers"
+    providers_dir.mkdir(parents=True, exist_ok=True)
+    return providers_dir
+
+
+def main():
+    """Build and install provider."""
+    provider_dir = Path(__file__).parent
+
+    # Build the provider
+    print("Building PyTorch CPU provider...")
+    build_provider()
+
+    # Determine binary name
+    binary_name = "tts-provider-pytorch-cpu"
+    if platform.system() == "Windows":
+        binary_name += ".exe"
+
+    # Source and destination paths
+    source = provider_dir / "dist" / binary_name
+    destination = get_providers_dir() / binary_name
+
+    # Copy to provider directory
+    print(f"Installing to {destination}...")
+    shutil.copy2(source, destination)
+
+    # Make executable on Unix systems
+    if platform.system() != "Windows":
+        destination.chmod(0o755)
+
+    print(f"✓ Provider installed successfully to {destination}")
+
+
+if __name__ == "__main__":
+    main()