fix: locale toggle shows current language, date inputs respect locale

- Language switcher now displays current locale (中文/English) instead of target
- Add lang attribute to date inputs for proper localization of native date picker

components/Sidebar.tsx

@@ -101,7 +101,7 @@ export function Sidebar() {
           style={{ color: "var(--text-muted)", background: "var(--row-hover)", border: "1px solid var(--surface-border)" }}
         >
           <Languages className="h-3.5 w-3.5" />
-          <span className="font-medium">{locale === "zh" ? "English" : "中文"}</span>
+          <span className="font-medium">{locale === "zh" ? "中文" : "English"}</span>
         </button>
 
         {/* Status */}

components/TimeRangeSelector.tsx

@@ -8,7 +8,7 @@ import { useTimeRange } from "@/lib/time-range-context";
 import { useI18n } from "@/lib/i18n";
 
 export function TimeRangeSelector() {
-  const { t } = useI18n();
+  const { t, locale } = useI18n();
   const { range, setRange, customStart, customEnd, setCustomStart, setCustomEnd } = useTimeRange();
   const [showPopover, setShowPopover] = useState(false);
   const [localStart, setLocalStart] = useState(customStart);
@@ -126,6 +126,7 @@ export function TimeRangeSelector() {
               </label>
               <input
                 type="date"
+                lang={locale === "zh" ? "zh-CN" : "en-US"}
                 value={localStart}
                 onChange={(e) => setLocalStart(e.target.value)}
                 className="input-glass w-full rounded-md px-3 py-1.5 text-xs font-[family-name:var(--font-geist-mono)]"
@@ -137,6 +138,7 @@ export function TimeRangeSelector() {
               </label>
               <input
                 type="date"
+                lang={locale === "zh" ? "zh-CN" : "en-US"}
                 value={localEnd}
                 onChange={(e) => setLocalEnd(e.target.value)}
                 className="input-glass w-full rounded-md px-3 py-1.5 text-xs font-[family-name:var(--font-geist-mono)]"