fix: parse YYYY-MM month filter correctly in attendance history

The frontend sends month as "YYYY-MM" but the route handler was passing
it through Number() which parsed only the year portion, causing the
service to ignore the month filter entirely.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "app-ts",
-  "version": "1.5.8",
+  "version": "1.5.9",
   "description": "",
   "main": "dist/server.js",
   "scripts": {