Migrate snapshot storage from IndexedDB to server-side JSON files (v2.0.0)

Snapshots are now stored as individual JSON files on the server under
data/snapshots/, making them persistent across browsers and resilient
to browser data loss. Existing IndexedDB data is auto-migrated on
first load.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -1,7 +1,7 @@
 [project]
 name = "comfyui-snapshot-manager"
 description = "Automatically snapshots workflow state with a sidebar to browse and restore previous versions."
-version = "1.1.1"
+version = "2.0.0"
 license = {text = "MIT"}
 
 [project.urls]