feature: enable automatic emoji measurement workflow on v2.1 pushes

- Workflow now triggers on push to v2.1 branch
- Also triggers on changes to emoji-widths.json or measure-emoji-widths.sh
- Can still be manually triggered via workflow_dispatch
- Provides SSH access for interactive emoji width measurement on macOS

Author: cowwoc

.github/workflows/measure-emoji-widths-macos.yml

@@ -5,6 +5,13 @@
 name: Measure Emoji Widths (macOS)
 
 on:
+  push:
+    branches:
+      - v2.1
+    paths:
+      - '.github/workflows/measure-emoji-widths-macos.yml'
+      - 'plugin/emoji-widths.json'
+      - 'plugin/scripts/measure-emoji-widths.sh'
   workflow_dispatch:
     inputs:
       terminal_type: