Add model catalog with specifications for DA3 and MoGe-2 models

- Introduced ModelSpec dataclass to define model attributes.
- Added multiple models including DA3 Small, Base, Giant 1.1, Nested Giant Large 1.1, and MoGe-2 variants.
- Implemented functions to retrieve model details and metadata.
- Included BEN2 model specifications for background removal.

src/snapform/server/__init__.py

@@ -1,19 +1,6 @@
 """SnapForm Job Server without Blender dependencies."""
 
-import sys
-from pathlib import Path
-
-
-SERVER_DIRECTORY = Path(__file__).resolve().parent
-ADDON_DIRECTORY = SERVER_DIRECTORY.parent
-for import_directory in (SERVER_DIRECTORY, ADDON_DIRECTORY):
-    if str(import_directory) not in sys.path:
-        sys.path.insert(0, str(import_directory))
-
-try:
-    from ..blendjob import JobServer
-except ImportError:
-    from blendjob import JobServer
+from blendjob import JobServer
 
 from .model_manager import ModelManager, ModelSessionCache
 from .background import remove_background as _remove_background
@@ -36,6 +23,12 @@ def download_model(context, parameters):
     return manager.download(context, parameters["model"])
 
 
+@server.job("download-required-models")
+def download_required_models(context, parameters):
+    manager = context.resource("model_manager")
+    return manager.download_missing(context, parameters["models"])
+
+
 @server.job("debug-ben2")
 @server.job("remove-background")
 def remove_background(context, parameters):