fix(library-desk): reduce ollama health check to single API call

Previously called /api/tags twice (once for server check, once for
model check). Now reuses response from single call.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

services/library-desk/src/clients/ollama_client.py

@@ -298,13 +298,22 @@ class OllamaClient:
             True if healthy, False otherwise
         """
         try:
-            # Check server is up
+            # Check server is up and get models in one call
             response = await self.client.get(self.tags_url, timeout=5.0)
             response.raise_for_status()
+            data = response.json()
+            models = data.get("models", [])
 
             # Check model is available
-            models_available = await self.check_model_available()
-            if not models_available:
+            check_model = self.model
+            model_found = False
+            for m in models:
+                name = m.get("name", "")
+                if name == check_model or name.startswith(f"{check_model}:"):
+                    model_found = True
+                    break
+
+            if not model_found:
                 logger.warning(f"Model '{self.model}' not found in Ollama")
                 return False