Add fallback if ImageMagick is not available

CLAUDE.md

@@ -21,17 +21,20 @@ pytest tests/test_generate_gallery.py -v
 # Run a single test by name
 pytest tests/test_generate_gallery.py::test_needs_update_missing_target -v
 
-# Generate gallery (CLI entry point after install)
-gallery --config config.yaml --verbose
+# Generate gallery
+gallery generate --verbose
 
-# Generate gallery (legacy script)
-python generate_gallery.py --verbose
+# Generate with a non-default config
+gallery --config config.yaml generate --verbose
 
 # Incremental update for one source only
-gallery --source /path/to/plots --verbose
+gallery generate --source /path/to/plots --verbose
 
 # Clean regeneration
-gallery --clean --verbose
+gallery generate --clean --verbose
+
+# Launch TUI
+gallery tui
 
 # Serve output locally
 python -m http.server 8000 -d /web/kschmidt/public_html/
@@ -62,8 +65,9 @@ generate() [api.py]
 |------|------|
 | `gallery/api.py` | `generate()` — primary public entry point; orchestrates everything |
 | `gallery/builder.py` | `build_gallery()` — recursive traversal; `get_template()`, `copy_assets()` |
-| `gallery/config.py` | `GalleryConfig`, `GallerySource`, `GalleryDefaults` dataclasses; YAML loading |
-| `gallery/cli.py` | CLI (`gallery` command) wrapping `generate()` |
+| `gallery/config/__init__.py` | `GalleryConfig`, `GallerySource`, `ConfigManager` dataclasses; YAML loading |
+| `gallery/cli.py` | CLI (`gallery` command) with subcommands: `generate`, `config`, `tui`, `install-completion` |
+| `gallery/tui.py` | TUI (`gallery tui`) built with Textual; interactive config editor + generation |
 | `gallery/utils/processing.py` | PDF→PNG via ImageMagick subprocess; `needs_update()` timestamp check; `render_gallery_page()` |
 | `gallery/utils/metadata.py` | Load/merge/cache YAML+JSON metadata; per-plot metadata resolution |
 | `gallery/utils/stats.py` | Directory size/count statistics |