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

public/index.html

@@ -42,6 +42,7 @@ placeholder="Enter address, intersection (e.g., Main St & Second St, City), or l
                         <label for="description">Additional Details (Optional)</label>
                         <textarea id="description" name="description" rows="3" 
                                 placeholder="Number of vehicles, time observed, etc."></textarea>
+                        <small class="input-help">Keep descriptions appropriate and relevant to road conditions. Submissions with inappropriate language will be rejected.</small>
                     </div>
                     
                     <button type="submit" id="submit-btn">