Optimize Docker workflow: only build on Dockerfile/requirements changes

- Add paths filter to only trigger on Dockerfile or requirements.txt changes
- Add workflow_dispatch for manual trigger when needed

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/docker-publish.yml

@@ -3,6 +3,11 @@ name: Docker
 on:
   push:
     branches: [ "main" ]
+    paths:
+      - 'Dockerfile'
+      - 'requirements.txt'
+  # Allow manual trigger for when you need to rebuild anyway
+  workflow_dispatch:
     
 env:
   REGISTRY: ghcr.io