chore: correct AI model name to Claude Sonnet 4.6 (Anthropic)

Author: oguyon

.agents/rules/git-workflow.md

@@ -77,8 +77,8 @@ chosen approach was selected over the alternatives.
 
 - **Model(s) used** — list every model that
   contributed code in this PR with exact version.
-  The current agent model is **Gemini 3.1 Pro**
-  (Google DeepMind). Ensure you report the
+  The current agent model is **Claude Sonnet 4.6**
+  (Anthropic). Ensure you report the
   correct model you are currently running as.
 - **User edits** — state whether the user made
   direct edits to source code alongside the