Use DEFAULT_MODEL constant for Anthropic API calls

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/keywords.mjs

@@ -3,7 +3,7 @@
  * One Claude call per search track using full profile + search config context
  */
 
-import { ANTHROPIC_API_URL } from './constants.mjs';
+import { ANTHROPIC_API_URL, DEFAULT_MODEL } from './constants.mjs';
 
 export async function generateKeywords(search, profile, apiKey) {
   if (!apiKey) throw new Error('ANTHROPIC_API_KEY not set');
@@ -48,7 +48,7 @@ Example format: ["query one", "query two", "query three"]`;
       'anthropic-version': '2023-06-01'
     },
     body: JSON.stringify({
-      model: 'claude-sonnet-4-6-20251101',
+      model: DEFAULT_MODEL,
       max_tokens: 1024,
       messages: [{ role: 'user', content: prompt }]
     })