重构为 HTTP SSO 扫码方案并引入 Vue3 前端

移除 Playwright 浏览器自动化，改用 passport/SSO HTTP 接口获取二维码与轮询登录；后端模块化拆分，前端替换为 Vue3 SPA。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/routes/spa.py

@@ -0,0 +1,55 @@
+import os
+
+from flask import Blueprint, abort, send_file, send_from_directory
+
+from backend.config import FRONTEND_DIST
+
+spa_bp = Blueprint("spa", __name__)
+
+
+def _frontend_index_path():
+    return os.path.join(FRONTEND_DIST, "index.html")
+
+
+def _has_frontend_build():
+    return os.path.isfile(_frontend_index_path())
+
+
+def serve_spa():
+    if not _has_frontend_build():
+        return (
+            "前端未构建，请在 frontend 目录执行: npm install && npm run build",
+            503,
+            {"Content-Type": "text/plain; charset=utf-8"},
+        )
+    return send_file(_frontend_index_path())
+
+
+@spa_bp.route("/")
+def index():
+    return serve_spa()
+
+
+@spa_bp.route("/debug")
+def debug_view():
+    return serve_spa()
+
+
+@spa_bp.route("/assets/<path:filename>")
+def frontend_assets(filename):
+    assets_dir = os.path.join(FRONTEND_DIST, "assets")
+    if not os.path.isdir(assets_dir):
+        abort(404)
+    return send_from_directory(assets_dir, filename)
+
+
+@spa_bp.route("/<path:path>")
+def spa_fallback(path):
+    if path.startswith("api/") or path == "qrcode.png":
+        abort(404)
+    if not _has_frontend_build():
+        abort(404)
+    dist_file = os.path.join(FRONTEND_DIST, path)
+    if os.path.isfile(dist_file):
+        return send_from_directory(FRONTEND_DIST, path)
+    return send_file(_frontend_index_path())