feat: add Gallery TUI for interactive configuration and generation

- Implemented a terminal user interface (TUI) for configuring the gallery generator using Textual.
- Included functionality to manage sources with add/remove
- Integrated a log pane to display generation output from subprocess calls.
- Implemented save functionality to persist configuration changes.

gallery/config/__init__.py

@@ -5,17 +5,50 @@ This module provides dataclasses for managing configuration, including
 defaults for gallery generation settings.
 """
 
+import shutil
 from dataclasses import dataclass, field
 from pathlib import Path
 from typing import Any, Dict, List, Optional, Union
 import yaml
+from platformdirs import user_config_dir
 
 
 def default_config_path() -> Path:
-    """Return the path to the package-bundled default config."""
+    """Return the path to the package-bundled read-only template config."""
     return Path(__file__).parent / "config.yaml"
 
 
+def user_config_path() -> Path:
+    """Return the user-level config path (~/.config/gallery/config.yaml).
+
+    Follows the XDG Base Directory spec via platformdirs:
+      Linux/macOS → ~/.config/gallery/config.yaml
+      Windows     → %APPDATA%/gallery/config.yaml
+    """
+    return Path(user_config_dir("gallery", appauthor=False)) / "config.yaml"
+
+
+def get_active_config_path() -> Path:
+    """Return the config path to use, with this precedence:
+
+      1. User config  (~/.config/gallery/config.yaml)  — if it exists
+      2. Package-bundled template                       — fallback
+    """
+    ucp = user_config_path()
+    return ucp if ucp.exists() else default_config_path()
+
+
+def ensure_user_config() -> Path:
+    """Ensure ~/.config/gallery/config.yaml exists, creating it from the
+    package template if needed.  Returns the path.
+    """
+    ucp = user_config_path()
+    if not ucp.exists():
+        ucp.parent.mkdir(parents=True, exist_ok=True)
+        shutil.copy(default_config_path(), ucp)
+    return ucp
+
+
 def _load_raw(path: Path) -> Dict[str, Any]:
     with open(path, "r") as f:
         return yaml.safe_load(f) or {}
@@ -182,7 +215,6 @@ class GalleryConfig:
 
         data = {
             "paths": {
-                "work_dir": str(Path.cwd()),
                 "web_folder": str(self.web_folder),
             },
             "gallery": {