feat: isolate profanity filter with separate database

- Create dedicated ProfanityFilter class with isolated SQLite database
- Separate profanity.db from main application database to prevent SQLITE_MISUSE errors
- Add comprehensive custom word management (CRUD operations)
- Implement advanced profanity detection with leetspeak and pattern matching
- Add admin UI for managing custom profanity words
- Add extensive test suites for both profanity filter and API routes
- Update server.js to use isolated profanity filter
- Add proper database initialization and cleanup methods
- Support in-memory databases for testing

Breaking changes:
- Profanity filter now uses separate database file
- Updated admin API endpoints for profanity management
- Enhanced profanity detection capabilities

package.json

@@ -5,7 +5,9 @@
   "main": "server.js",
   "scripts": {
     "start": "node server.js",
-    "dev": "nodemon server.js"
+    "dev": "nodemon server.js",
+    "test": "jest --runInBand --forceExit",
+    "test:coverage": "jest --coverage"
   },
   "dependencies": {
     "cors": "^2.8.5",
@@ -15,7 +17,9 @@
     "sqlite3": "^5.1.6"
   },
   "devDependencies": {
-    "nodemon": "^3.0.1"
+    "jest": "^29.7.0",
+    "nodemon": "^3.0.1",
+    "supertest": "^6.3.4"
   },
   "keywords": [
     "ice",