Restructure: move Vite project into app/, deploy build output to repo root

The webserver serves the repo checkout directly as static files, so
index.html at the repo root must be the production build (pointing at
hashed /assets/*.js) rather than the dev template (/src/main.tsx),
which was being served with an unrecognized application/octet-stream
MIME type and blocked by the browser.

- Move src/, public/, scripts/, server/, package.json, vite.config.ts,
  tsconfig.json, .env(.example), and the dev index.html into app/.
- Add app/scripts/deploy.mjs: copies app/dist/* into the repo root
  after every `vite build`, cleaning up stale hashed filenames.
- Wire it into `npm run build` (app/package.json).
- Update run.sh to operate from app/, and .gitignore for the new layout.
- Commit the current build output (index.html, assets/, manifest,
  sw.js, workbox-*.js, favicon.svg, icons/, LICENSE) to the repo root.
- Update README with the new project layout and deployment model.

run.sh

@@ -4,7 +4,7 @@
 #
 #   ./run.sh              # dev server  -> http://localhost:5173
 #   ./run.sh dev          # same as above
-#   ./run.sh build        # production build into dist/
+#   ./run.sh build        # production build, deployed into the repo root
 #   ./run.sh serve        # build if needed, then host + proxy /api/* (needs HERMES_TARGET)
 #   ./run.sh preview      # build, then serve the build with vite preview
 #   ./run.sh icons        # regenerate the PWA icon set
@@ -17,7 +17,7 @@
 #
 set -eu
 
-cd "$(dirname "$0")"
+cd "$(dirname "$0")/app"
 
 MODE="${1:-dev}"
 
@@ -54,7 +54,7 @@ case "$MODE" in
   build)
     ensure_deps
     ensure_icons
-    log "Building..."
+    log "Building and deploying to repo root..."
     exec npm run build
     ;;
   serve)