Preserve existing configuration during reinstallation

When reinstalling LBRY Downloader, the setup script now:
- Checks if config.yaml exists in ~/Documents/lbry-downloads/
- If found, asks user if they want to use existing config
- If yes, skips all configuration prompts and preserves channels/settings
- If no, proceeds with normal interactive setup

This prevents users from having to re-enter all their channels
and settings every time they reinstall or update the tool.

Fixes #2 - Config is no longer overwritten on reinstall.

setup.py

@@ -589,6 +589,46 @@ def run_setup() -> None:
         print_error("Failed to install Python dependencies")
         sys.exit(1)
 
+    # Check for existing configuration
+    default_download_location = "~/Documents/lbry-downloads"
+    config_path = Path(default_download_location).expanduser() / "config.yaml"
+
+    if config_path.exists():
+        print_header("Existing Configuration Found")
+        print_info(f"Found existing config: {config_path}")
+        print_info("This will preserve your channels and settings")
+
+        response = input("Use existing configuration? (Y/n): ").strip().lower()
+        if response != "n":
+            print_success("Using existing configuration")
+            download_location = default_download_location
+            # Ensure necessary directories exist
+            Path(download_location).expanduser().mkdir(parents=True, exist_ok=True)
+            (Path(download_location).expanduser() / "state").mkdir(exist_ok=True)
+            (Path(download_location).expanduser() / "channels").mkdir(exist_ok=True)
+            # Store config_path for final message
+            config_path = Path(download_location).expanduser() / "config.yaml"
+        else:
+            # User wants to reconfigure
+            download_location = get_download_location()
+            channels = get_channels()
+            download_limit = get_download_limit()
+
+            # Create config file
+            print_header("Creating Configuration")
+            config_content = create_config(download_location, channels, download_limit)
+
+            config_path = Path(download_location).expanduser() / "config.yaml"
+            config_path.parent.mkdir(parents=True, exist_ok=True)
+            config_path.write_text(config_content)
+            print_success(f"Created configuration: {config_path}")
+
+            # Create necessary directories
+            (config_path.parent / "state").mkdir(exist_ok=True)
+            (config_path.parent / "channels").mkdir(exist_ok=True)
+            print_success("Created directory structure")
+    else:
+        # No existing config, proceed with normal setup
         # Get configuration from user
         download_location = get_download_location()
         channels = get_channels()
@@ -608,6 +648,11 @@ def run_setup() -> None:
         (config_path.parent / "channels").mkdir(exist_ok=True)
         print_success("Created directory structure")
 
+    # Create necessary directories
+    (config_path.parent / "state").mkdir(exist_ok=True)
+    (config_path.parent / "channels").mkdir(exist_ok=True)
+    print_success("Created directory structure")
+
     # Create launcher scripts
     create_launcher_script(install_dir, venv_path)