Set OpenAI as default provider (Claude on standby)

Claude API key is present but not used as primary until verified.
Fallback still attempts Claude if OpenAI fails.

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

Author: satya-blend360

.github/workflows/ai-review.yml

@@ -8,7 +8,7 @@ on:
       ai_provider:
         description: 'Primary AI provider for this run'
         required: false
-        default: 'claude'
+        default: 'openai'
         type: choice
         options:
           - claude
@@ -21,7 +21,7 @@ jobs:
       pull-requests: write
     # Priority: manual dispatch input > repo variable (vars.AI_PROVIDER) > default 'claude'
     env:
-      AI_PROVIDER: ${{ github.event_name == 'workflow_dispatch' && inputs.ai_provider || vars.AI_PROVIDER || 'claude' }}
+      AI_PROVIDER: ${{ github.event_name == 'workflow_dispatch' && inputs.ai_provider || vars.AI_PROVIDER || 'openai' }}
 
     steps:
       - name: Checkout repo