ci: run Claude Code workflow on Fable 5

Set the model explicitly to claude-fable-5 so @claude mentions on
issues and PRs are handled by Anthropic's most capable model instead
of the action's default (Opus 4.8).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: loothero

.github/workflows/claude.yml

@@ -40,8 +40,8 @@ jobs:
           additional_permissions: |
             actions: read
           
-          # Optional: Specify model (defaults to Claude Sonnet 4, uncomment for Claude Opus 4)
-          # model: "claude-opus-4-20250514"
+          # Use Claude Fable 5, Anthropic's most capable model, for all reviews
+          model: "claude-fable-5"
 
           # Optional: Customize the trigger phrase (default: @claude)
           # trigger_phrase: "/claude"