chore: update dependencies and enhance vacation request component

- Updated convex-svelte to version 0.0.12 and convex to version 1.28.2 for improved functionality.
- Refactored the vacation request component to enhance loading states and error handling.
- Implemented derived states for better management of loading and error states.
- Improved calendar initialization logic and cleanup processes for better performance and reliability.

package.json

@@ -8,7 +8,7 @@
 			"packages/*"
 		],
 		"catalog": {
-			"convex": "^1.28.0",
+			"convex": "^1.28.2",
 			"typescript": "^5.9.2",
 			"better-auth": "1.3.27",
 			"eslint": "^9.39.1",