Add filtering and sorting to question bank

- Add search, category, and type filters to questions API
- Add clickable sortable table headers with sort indicators
- Add filter controls UI with clear filters button

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/routes/questions.py

@@ -7,8 +7,65 @@ bp = Blueprint('questions', __name__, url_prefix='/api/questions')
 
 @bp.route('', methods=['GET'])
 def list_questions():
-    """Get all questions"""
-    questions = Question.query.order_by(Question.created_at.desc()).all()
+    """Get all questions with optional filtering and sorting
+
+    Query parameters:
+    - search: Search in question content and answer (case-insensitive)
+    - category: Filter by category name (exact match, or 'none' for uncategorized)
+    - type: Filter by question type (text, image, youtube_audio)
+    - sort_by: Field to sort by (created_at, category, type, question_content, answer)
+    - sort_order: Sort direction (asc, desc) - default: desc
+    """
+    query = Question.query
+
+    # Search filter
+    search = request.args.get('search', '').strip()
+    if search:
+        search_pattern = f'%{search}%'
+        query = query.filter(
+            db.or_(
+                Question.question_content.ilike(search_pattern),
+                Question.answer.ilike(search_pattern)
+            )
+        )
+
+    # Category filter
+    category = request.args.get('category', '').strip()
+    if category:
+        if category.lower() == 'none':
+            query = query.filter(Question.category.is_(None))
+        else:
+            query = query.filter(Question.category == category)
+
+    # Type filter
+    question_type = request.args.get('type', '').strip()
+    if question_type:
+        try:
+            query = query.filter(Question.type == QuestionType(question_type))
+        except ValueError:
+            pass  # Invalid type, ignore filter
+
+    # Sorting
+    sort_by = request.args.get('sort_by', 'created_at').strip()
+    sort_order = request.args.get('sort_order', 'desc').strip().lower()
+
+    # Map sort_by to column
+    sort_columns = {
+        'created_at': Question.created_at,
+        'category': Question.category,
+        'type': Question.type,
+        'question_content': Question.question_content,
+        'answer': Question.answer,
+    }
+
+    sort_column = sort_columns.get(sort_by, Question.created_at)
+
+    if sort_order == 'asc':
+        query = query.order_by(sort_column.asc())
+    else:
+        query = query.order_by(sort_column.desc())
+
+    questions = query.all()
     return jsonify([q.to_dict(include_answer=True) for q in questions]), 200