perf(zopk): Cache dla grafu relacji (TTL 5 min)

- Dodano in-memory cache dla API /api/zopk/knowledge/graph/data
- Cache key oparty o parametry: entity_type, min_cooccurrence, limit
- TTL = 300 sekund (5 minut)
- Flaga 'cached' w odpowiedzi informuje czy dane z cache

Korzyść: Drugie i kolejne ładowania grafu są natychmiastowe.

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

app.py

@@ -11921,23 +11921,43 @@ def admin_zopk_knowledge_graph():
     return render_template('admin/zopk_knowledge_graph.html')
 
 
+# Cache for graph data (in-memory with TTL)
+_graph_cache = {}
+_GRAPH_CACHE_TTL = 300  # 5 minutes
+
+
 @app.route('/api/zopk/knowledge/graph/data')
 @login_required
 def api_zopk_knowledge_graph_data():
-    """Get graph data for entity co-occurrence visualization."""
+    """Get graph data for entity co-occurrence visualization.
+
+    Uses in-memory cache with 5 minute TTL to avoid recalculating
+    co-occurrences on every request.
+    """
+    import time
+
     if not current_user.is_admin:
         return jsonify({'success': False, 'error': 'Brak uprawnień'}), 403
 
     from sqlalchemy import text, func
     from database import ZOPKKnowledgeEntity, ZOPKKnowledgeEntityMention
 
+    # Build cache key from parameters
+    entity_type = request.args.get('entity_type', '')
+    min_cooccurrence = int(request.args.get('min_cooccurrence', 3))
+    limit = min(int(request.args.get('limit', 100)), 500)
+    cache_key = f"graph:{entity_type}:{min_cooccurrence}:{limit}"
+
+    # Check cache
+    if cache_key in _graph_cache:
+        cached_data, cached_time = _graph_cache[cache_key]
+        if time.time() - cached_time < _GRAPH_CACHE_TTL:
+            # Return cached data with cache indicator
+            cached_data['cached'] = True
+            return jsonify(cached_data)
+
     db = SessionLocal()
     try:
-        # Filter parameters
-        entity_type = request.args.get('entity_type', '')
-        min_cooccurrence = int(request.args.get('min_cooccurrence', 3))
-        limit = min(int(request.args.get('limit', 100)), 500)
-
         # Get top entities by mentions
         entities_query = db.query(ZOPKKnowledgeEntity).filter(
             ZOPKKnowledgeEntity.mentions_count >= 5
@@ -12008,15 +12028,22 @@ def api_zopk_knowledge_graph_data():
                     'verified': e.is_verified
                 })
 
-        return jsonify({
+        # Build response
+        response_data = {
             'success': True,
             'nodes': nodes,
             'links': links,
             'stats': {
                 'total_nodes': len(nodes),
                 'total_links': len(links)
-            }
-        })
+            },
+            'cached': False
+        }
+
+        # Save to cache
+        _graph_cache[cache_key] = (response_data.copy(), time.time())
+
+        return jsonify(response_data)
 
     except Exception as e:
         logger.error(f"Error getting graph data: {e}")