Add branch selection to bug report template

Added a dropdown field to allow bug reporters to specify which branch they are using (stable or main), with stable as the default. This will help with debugging and tracking branch-specific issues.

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

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

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -21,6 +21,18 @@ body:
     validations:
       required: true
 
+  - type: dropdown
+    id: branch
+    attributes:
+      label: Branch
+      description: Which branch are you using?
+      options:
+        - "stable"
+        - "main"
+      default: 0
+    validations:
+      required: true
+
   - type: dropdown
     id: severity
     attributes: