refactor: remove biome configuration and update dependencies

- Deleted the obsolete biome.json file to streamline project configuration.
- Updated package.json and bun.lock to include new ESLint and Prettier dependencies for improved code quality and consistency.
- Added ESLint configuration package for better linting support across the project.
- Cleaned up various package dependencies to ensure a more maintainable and efficient codebase.

packages/backend/eslint.config.js

@@ -0,0 +1,7 @@
+import { config } from '@sgse-app/eslint-config/convex';
+import { defineConfig } from 'eslint/config';
+ 
+/** @type {import("eslint").Linter.Config} */
+export default defineConfig([
+  ...config,
+]);

packages/backend/package.json

@@ -9,6 +9,7 @@
   "license": "ISC",
   "description": "",
   "devDependencies": {
+    "@sgse-app/eslint-config": "*",
     "@types/cookie": "^1.0.0",
     "@types/estree": "^1.0.8",
     "@types/nodemailer": "^7.0.3",
@@ -17,7 +18,8 @@
     "@types/pako": "^2.0.4",
     "@types/raf": "^3.4.3",
     "@types/trusted-types": "^2.0.7",
-    "typescript": "catalog:"
+    "typescript": "catalog:",
+    "eslint": "catalog:"
   },
   "dependencies": {
     "@convex-dev/better-auth": "^0.9.7",