Update SnapForm to version 0.10.10 and add technical documentation

- Bump SnapForm version in uv.lock from 0.9.30 to 0.10.10.
- Introduce comprehensive technical documentation for SnapForm, detailing features, usage instructions, and development guidelines.

src/snapform/preferences.py

@@ -35,6 +35,14 @@ class SnapFormPreferences(bpy.types.AddonPreferences):
         ),
         default="CPU" if sys.platform == "darwin" else "CU128",
     )
+    pypi_index_url: bpy.props.StringProperty(
+        name="PyPI Index",
+        description=(
+            "Package index for the isolated Runtime; leave empty to auto-detect "
+            "with mirror fallback. Example: https://pypi.tuna.tsinghua.edu.cn/simple"
+        ),
+        default="",
+    )
 
     def draw(self, _context):
         from .operators import active_job
@@ -44,6 +52,7 @@ class SnapFormPreferences(bpy.types.AddonPreferences):
         layout.prop(self, "storage_root")
         layout.prop(self, "uv_executable")
         layout.prop(self, "torch_backend")
+        layout.prop(self, "pypi_index_url")
         layout.separator()
         layout.label(text=f"Runtime: {runtime_directory()}")
         if runtime_ready():