fix(mobile): replace App-Plus unsupported date and query APIs

`URLSearchParams` is absent from the App-Plus JS core, and
`toLocaleDateString('sv-SE', { timeZone: 'Asia/Shanghai' })` depends on full
ICU data that the App runtime does not ship, so the work-result pages built
either a broken query string or the device-local date.

Build query strings with `encodeURIComponent`, and centralise the business day
in `currentShanghaiDate()`, which shifts the epoch by a fixed UTC+8 offset
before slicing the ISO date. Asia/Shanghai has no DST, so the fixed offset is
exact rather than an approximation.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

mobile-uni/src/pages/supervisor/review/index.vue

@@ -528,9 +528,9 @@ const markReviewed = async () => {
       nextReason: nextScenarioId.value ? nextReason.value.trim() : undefined,
       confirmedGrowthLevel: confirmedGrowthLevel.value || undefined
     });
-    const params = new URLSearchParams({ id: String(detail.value.id) });
-    if (assignedScenario) params.set('assigned', assignedScenario);
-    uni.redirectTo({ url: `/pages/supervisor/review/done?${params.toString()}` });
+    const params = [`id=${encodeURIComponent(String(detail.value.id))}`];
+    if (assignedScenario) params.push(`assigned=${encodeURIComponent(assignedScenario)}`);
+    uni.redirectTo({ url: `/pages/supervisor/review/done?${params.join('&')}` });
   } catch (error) {
     handleRequestError(error, '标记失败');
   } finally {