fix: refine earth hud structure and bun startup flow

- refactor the /earth HUD into class-first CSS layers with dedicated base, hud, and toolbar responsibilities
- clean up Earth markup and runtime DOM hooks so shared panel, toolbar, tooltip, and status classes stay consistent after dynamic updates
- keep HUD scaling configurable through extracted constants and remove leftover legacy panel/toolbar styling paths
- make planet.sh self-bootstrap Bun and uv by prepending local runtime bins to PATH and auto-installing missing tools in fresh environments
- document Bun as the frontend package manager of record and sync repository version metadata to 0.24.1

scripts/bootstrap-dev.sh

@@ -106,7 +106,10 @@ print_next_steps() {
     echo "下一步建议:"
     echo "  1. cd \"$ROOT_DIR\""
     echo "  2. uv run pytest backend/tests/test_api.py -q -s"
-    echo "  3. ./planet.sh start"
+    echo "  3. cd \"$ROOT_DIR/frontend\" && bun run build"
+    echo "  4. cd \"$ROOT_DIR\" && ./planet.sh start"
+    echo ""
+    echo "前端统一使用 Bun，不使用 npm/pnpm/yarn。"
 }
 
 main() {