feat: implement comprehensive email system with rate limiting and extensive test suite

- Add robust email service with rate limiting and configuration management
- Implement shared rate limiter utility for consistent API protection
- Create comprehensive test suite for core processing pipeline
- Add API tests for dashboard metrics and authentication routes
- Fix date range picker infinite loop issue
- Improve session lookup in refresh sessions API
- Refactor session API routing with better code organization
- Update processing pipeline status monitoring
- Clean up leftover files and improve code formatting

tsconfig.json

@@ -25,7 +25,14 @@
     "strictNullChecks": true,
     "target": "es5"
   },
-  "exclude": ["node_modules", "check-*.ts", "migrate-*.ts", "fix-*.ts", "debug-*.ts", "test-*.ts"],
+  "exclude": [
+    "node_modules",
+    "check-*.ts",
+    "migrate-*.ts",
+    "fix-*.ts",
+    "debug-*.ts",
+    "test-*.ts"
+  ],
   "include": [
     "next-env.d.ts",
     "**/*.ts",