Add lazy initialization for Anthropic client

- Re-initialize client from env if not set during first call
- Provides better error message pointing to HF Spaces Secrets
- Fixes 'Anthropic client not initialized' error

src/utils/ai_client.py

@@ -116,7 +116,17 @@ class AIClient:
     ) -> str:
         """Generate using Anthropic Claude"""
         if not self.anthropic_client:
-            raise RuntimeError("Anthropic client not initialized")
+            # Try to re-initialize from environment
+            anthropic_key = os.getenv("ANTHROPIC_API_KEY")
+            if anthropic_key:
+                print(f"Re-initializing Anthropic client with key: {anthropic_key[:10]}...")
+                try:
+                    self.anthropic_client = anthropic.Anthropic(api_key=anthropic_key)
+                    print("✅ Anthropic client re-initialized successfully")
+                except Exception as e:
+                    raise RuntimeError(f"Failed to re-initialize Anthropic client: {e}")
+            else:
+                raise RuntimeError("Anthropic client not initialized. Set ANTHROPIC_API_KEY in HF Spaces Secrets.")
 
         messages = [{"role": "user", "content": prompt}]