Replace deploy workflow with portable Windows release build

- Remove old Docker-based deploy.yml
- Add release.yml: builds portable ZIP on tag push, uploads to Gitea
- Add build-dist.ps1: downloads embedded Python, installs deps, bundles app
- Add scrollbar-gutter: stable to prevent layout shift

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/wled_controller/static/css/base.css

@@ -81,6 +81,7 @@ html {
     background: var(--bg-color);
     overflow-y: scroll;
     scroll-behavior: smooth;
+    scrollbar-gutter: stable;
 }
 
 body {