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,
+]);