feat: 现代化翻页组件 + 完整项目更新

- 新增 Pagination 通用组件：首页/上一页/页码/下一页/末页导航
- PickModal 和 SwapModal 集成分页功能，每页20项
- 搜索/筛选切换自动回到第1页
- 现代化CSS样式：hover浮起动效、主色高亮、移动端适配
- 新增 dashboard、admin 管理模板
- 菜系(cuisine)模型和迁移
- 构建脚本 build.py 支持 PyInstaller 打包
- 前端资源重新构建

backend/meals/views_spa.py

@@ -0,0 +1,56 @@
+import mimetypes
+import os
+
+from django.http import FileResponse, HttpResponseNotFound
+from django.views.decorators.csrf import ensure_csrf_cookie
+
+_FE_DIR_CACHE = None
+_INDEX_CACHE = None
+
+
+def _get_frontend_dir():
+    global _FE_DIR_CACHE
+    if _FE_DIR_CACHE is None:
+        import sys
+        if getattr(sys, 'frozen', False):
+            _FE_DIR_CACHE = os.path.join(sys._MEIPASS, 'backend', 'static', 'frontend')
+        else:
+            env_dir = os.environ.get('FRONTEND_DIR')
+            if env_dir and os.path.isdir(env_dir):
+                _FE_DIR_CACHE = env_dir
+            else:
+                _FE_DIR_CACHE = os.path.join(
+                    os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
+                    'static', 'frontend',
+                )
+    return _FE_DIR_CACHE
+
+
+def _get_index_path():
+    global _INDEX_CACHE
+    if _INDEX_CACHE is None:
+        p = os.path.join(_get_frontend_dir(), 'index.html')
+        _INDEX_CACHE = p if os.path.isfile(p) else ''
+    return _INDEX_CACHE
+
+
+def _serve_file(filepath):
+    ct, _ = mimetypes.guess_type(filepath)
+    return FileResponse(open(filepath, 'rb'), content_type=ct or 'application/octet-stream')
+
+
+@ensure_csrf_cookie
+def spa_serve(request, path=None):
+    """Serve built React assets or fall back to index.html."""
+    fdir = _get_frontend_dir()
+    req_path = (path or '').lstrip('/')
+
+    if req_path:
+        target = os.path.normpath(os.path.join(fdir, req_path))
+        if target.startswith(os.path.normpath(fdir)) and os.path.isfile(target):
+            return _serve_file(target)
+
+    index = _get_index_path()
+    if index:
+        return _serve_file(index)
+    return HttpResponseNotFound('Frontend not built. Run build.py first.')