chore: remove obsolete Android app configuration files

- Deleted build.gradle.kts, gradle.properties, and gradlew files as part of the cleanup process.
- Removed local.properties and various generated files from the .gradle directory to streamline the project structure.
- Cleared out unnecessary build artifacts and intermediate files to improve project maintainability.

frontend/package.json

@@ -17,6 +17,7 @@
     "jspdf": "^4.0.0",
     "jspdf-autotable": "^5.0.2",
     "node-cron": "^4.2.1",
+    "pdfjs-dist": "^5.6.205",
     "socket.io-client": "^4.8.1",
     "sortablejs": "^1.15.3",
     "vue": "^3.2.13",