Revert "fix(electron): prevent beforeunload prompt by using autosave (#642)" (#646)

This reverts commit e7c29fb410.

The PR introduced an IndexedDB error: 'Failed to execute transaction on IDBDatabase: The database connection is closing.'

lib/session-storage.ts

@@ -75,18 +75,6 @@ export function isIndexedDBAvailable(): boolean {
     }
 }
 
-// Check if IndexedDB is actually usable (not just present).
-export async function isIndexedDBUsable(): Promise<boolean> {
-    if (!isIndexedDBAvailable()) return false
-    try {
-        const db = await getDB()
-        db.close()
-        return true
-    } catch {
-        return false
-    }
-}
-
 // CRUD Operations
 export async function getAllSessionMetadata(): Promise<SessionMetadata[]> {
     if (!isIndexedDBAvailable()) return []