feat: align portal center panel with side cards + redesign login page

- Portal: wrap .panel-head in matching card (border, radius, shadow) with
  cyan->purple left accent bar; h2 28px -> 20px; description right-aligned
  with vertical divider; top edge now aligns with side-menu & links-panel
- Login: switch from absolute-positioned icons to el-input prefix slot;
  layout brand row (logo + title + uppercase subtitle); add form-title
  section with gradient bar; consistent cyan focus; gradient button;
  dashed top divider for back-link; card width 420 -> 460
- Add .gitignore (node_modules, dist, __pycache__, .env, etc.)

backend/app.py

@@ -0,0 +1,57 @@
+"""App factory. Serves API + (in production) the built Vue frontend."""
+import os
+
+from flask import Flask, send_from_directory
+
+from config import BASE_DIR, Config, UPLOAD_DIR, UPLOAD_URL_PREFIX
+from extensions import db
+
+DIST_DIR = os.path.join(BASE_DIR, "..", "frontend", "dist")
+
+
+def create_app():
+    app = Flask(__name__, static_folder=None)
+    app.config.from_object(Config)
+
+    os.makedirs(os.path.join(BASE_DIR, "instance"), exist_ok=True)
+    db.init_app(app)
+    db.app = app
+
+    from routes import auth as auth_routes
+    from routes import portal as portal_routes
+    from routes import admin as admin_routes
+    app.register_blueprint(auth_routes.bp)
+    app.register_blueprint(portal_routes.bp)
+    app.register_blueprint(admin_routes.bp)
+
+    @app.route("/api/health")
+    def health():
+        return {"status": "ok"}
+
+    # Serve uploaded files
+    os.makedirs(Config.UPLOAD_FOLDER, exist_ok=True)
+    @app.route(UPLOAD_URL_PREFIX + "/<path:filename>")
+    def uploaded_file(filename):
+        return send_from_directory(Config.UPLOAD_FOLDER, filename)
+
+    # ---- Serve built Vue SPA in production (after `npm run build`) ----
+    if os.path.isdir(DIST_DIR):
+        @app.route("/", defaults={"path": ""})
+        @app.route("/<path:path>")
+        def spa(path):
+            full = os.path.join(DIST_DIR, path)
+            if path and os.path.isfile(full):
+                return send_from_directory(DIST_DIR, path)
+            return send_from_directory(DIST_DIR, "index.html")
+
+    return app
+
+
+app = create_app()
+
+if __name__ == "__main__":
+    with app.app_context():
+        db.create_all()
+        from seed import seed_all
+        seed_all()
+    app.run(host="0.0.0.0", port=8090, debug=False)