fix(recipes): persist source_path in SQLite cache and eliminate source_url redundancy

- Add source_path column to PersistentRecipeCache SQLite schema with
  migration for existing databases (ALTER TABLE ADD COLUMN)
- Backfill source_path from recipe JSON files on first startup after
  migration to avoid requiring manual cache rebuild
- Remove all source_url recipe field references (import_remote_recipe,
  import_from_url, check_image_exists, enrichment, batch_import)
  and consolidate on source_path as the single source of truth
- Add civitai.green to supported Civitai page hosts
- Register check-image-exists and import-from-url recipe endpoints

py/routes/recipe_route_registrar.py

@@ -70,6 +70,10 @@ ROUTE_DEFINITIONS: tuple[RouteDefinition, ...] = (
         "POST", "/api/lm/recipes/batch-import/directory", "start_directory_import"
     ),
     RouteDefinition("POST", "/api/lm/recipes/browse-directory", "browse_directory"),
+    RouteDefinition(
+        "GET", "/api/lm/recipes/check-image-exists", "check_image_exists"
+    ),
+    RouteDefinition("GET", "/api/lm/recipes/import-from-url", "import_from_url"),
 )