Expose project version history

AGENTS.md

@@ -237,6 +237,9 @@ not change the project revision or undo/redo stacks. Restoring a server-stored
 snapshot verifies its checksum and the current-state hash, replaces supported
 project data atomically and records a new `restore` revision with a complete
 inverse command. Restore can therefore be undone and redone after a restart.
+The project page exposes an initially collapsed German snapshot/timeline UI
+with explicit restore confirmation and cursor-based loading of older revision
+metadata.
 Insertions and generated move targets use client-generated stable UUIDs, and
 undo restores the same ids from complete server snapshots. The tree response
 supplies the optimistic `currentRevision`; obsolete direct field PATCH,
@@ -308,7 +311,7 @@ Users must be able to override sizing suggestions.
 
 ## Current Deferred Work
 
-- snapshot UI and periodic snapshot policy
+- periodic snapshot and retention policy
 - Revit/CSV/IFCGUID round-trip
 - full electrical sizing
 - multi-user/PostgreSQL operation