Restore full pipeline: 3-step summarization, formatting, PDF/DOCX generation

services/ai/base_provider.py

@@ -23,6 +23,11 @@ class AIProvider(ABC):
         """Classify content into categories"""
         pass
 
+    @abstractmethod
+    def generate_text(self, prompt: str, **kwargs) -> str:
+        """Generate text from prompt"""
+        pass
+
     @abstractmethod
     def is_available(self) -> bool:
         """Check if provider is available and configured"""