移除 v1.5.6 升级公告横幅

- ScanTerminalDashboard: 删除 showAnnouncement 状态、localStorage 检测逻辑、渲染代码
- ScanTerminalShellParts: 删除 ScanUpgradeAnnouncement 组件

frontend/components/dashboard/ScanTerminalDashboard.tsx

@@ -28,7 +28,6 @@ import {
   ScanPaywallModal,
   ScanTerminalLoadingScreen,
   ScanTerminalTopBar,
-  ScanUpgradeAnnouncement,
   type ScanTerminalContentView,
 } from "@/components/dashboard/scan-terminal/ScanTerminalShellParts";
 import { findDetailForCity } from "@/components/dashboard/scan-terminal/city-detail-utils";
@@ -92,7 +91,6 @@ function ScanTerminalScreen() {
   const [activeView, setActiveView] = useState<ScanTerminalContentView>("map");
   const [mapSelectedCityName, setMapSelectedCityName] = useState<string | null>(null);
   const [showScanPaywall, setShowScanPaywall] = useState(false);
-  const [showAnnouncement, setShowAnnouncement] = useState(false);
   const [isMobileViewport, setIsMobileViewport] = useState(false);
 
   useEffect(() => {
@@ -111,22 +109,6 @@ function ScanTerminalScreen() {
     return () => media.removeEventListener("change", syncMobileViewport);
   }, []);
 
-  useEffect(() => {
-    if (isMobileViewport) {
-      setShowAnnouncement(false);
-      return;
-    }
-    const key = "polyweather_v156_announcement_seen_at";
-    const seen = localStorage.getItem(key);
-    const now = Date.now();
-    if (!seen) {
-      localStorage.setItem(key, String(now));
-      setShowAnnouncement(true);
-      return;
-    }
-    const elapsed = now - Number(seen);
-    setShowAnnouncement(elapsed < 3 * 24 * 60 * 60 * 1000);
-  }, [isMobileViewport]);
   const userLocalTime = useUserLocalClock();
   const { setThemeMode, themeMode } = useScanTerminalTheme();
   const lastMapSelectedCityRef = useRef<string>("");
@@ -444,19 +426,6 @@ function ScanTerminalScreen() {
             userLocalTime={userLocalTime}
           />
 
-          {showAnnouncement && !isMobileViewport ? (
-            <ScanUpgradeAnnouncement
-              isEn={isEn}
-              onDismiss={() => {
-                localStorage.setItem(
-                  "polyweather_v156_announcement_seen_at",
-                  String(Date.now() + 90 * 24 * 60 * 60 * 1000),
-                );
-                setShowAnnouncement(false);
-              }}
-            />
-          ) : null}
-
           <section className="scan-list-section">
             <div className="scan-list-header">
               <div className="scan-list-tabs" role="tablist" aria-label={isEn ? "Content view" : "内容视图"}>

frontend/components/dashboard/scan-terminal/ScanTerminalShellParts.tsx

@@ -160,50 +160,6 @@ export function ScanTerminalTopBar({
   );
 }
 
-export function ScanUpgradeAnnouncement({
-  isEn,
-  onDismiss,
-}: {
-  isEn: boolean;
-  onDismiss: () => void;
-}) {
-  return (
-    <section
-      className="scan-upgrade-announcement"
-      aria-label={isEn ? "Upgrade announcement" : "升级公告"}
-    >
-      <div className="scan-upgrade-announcement-copy">
-        <span>{isEn ? "v1.5.6 upgrade" : "v1.5.6 升级公告"}</span>
-        <strong>
-          {isEn
-            ? "Scan terminal is upgraded to v1.5.6"
-            : "决策终端已升级到 v1.5.6"}
-        </strong>
-        <p>
-          {isEn
-            ? "City decision cards have been redesigned with a compact hero layout and consistent DEB data source. Sticky headers are removed for smoother scrolling."
-            : "城市决策卡 hero 布局重新设计，三指标并列对比更直观；DEB 数据源统一不再出现不一致；去除顶部固定效果滚动更流畅。"}
-        </p>
-      </div>
-      <ul>
-        <li>{isEn ? "Redesigned decision card hero" : "重设计城市决策卡 hero 布局"}</li>
-        <li>{isEn ? "Unified DEB data source" : "统一 DEB 数据源"}</li>
-        <li>{isEn ? "Light theme coverage" : "亮色主题补全覆盖"}</li>
-        <li>{isEn ? "HKO observatory AI read" : "香港天文台观测 AI 解读"}</li>
-        <li>{isEn ? "Smoother scrolling experience" : "滚动体验优化"}</li>
-      </ul>
-      <button
-        type="button"
-        className="scan-announcement-dismiss"
-        aria-label={isEn ? "Dismiss" : "关闭"}
-        onClick={onDismiss}
-      >
-        ✕
-      </button>
-    </section>
-  );
-}
-
 export function ScanPaywallModal({
   isEn,
   onClose,