Fix deployment to preserve data dir in place

Use find to delete all files except data directory instead of
moving to /tmp which fails due to sticky bit permissions.

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

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

.github/workflows/build.yml

@@ -31,11 +31,8 @@ jobs:
 
       - name: Deploy to /opt/immersive
         run: |
-          # Backup data directory if it exists
-          [ -d /opt/immersive/data ] && mv /opt/immersive/data /tmp/immersive-data
-
-          # Remove old files (except data which we moved)
-          rm -rf /opt/immersive/*
+          # Remove old files except data directory
+          find /opt/immersive -mindepth 1 -maxdepth 1 ! -name 'data' -exec rm -rf {} +
 
           # Copy built files to target
           cp -r . /opt/immersive/
@@ -43,9 +40,6 @@ jobs:
           # Remove unnecessary directories
           rm -rf /opt/immersive/.git /opt/immersive/.github
 
-          # Restore data directory
-          [ -d /tmp/immersive-data ] && mv /tmp/immersive-data /opt/immersive/data
-
           # Set permissions on start.sh
           chmod +x /opt/immersive/start.sh