fix: eliminate error flash on startup by distinguishing loading from error state

- Change TQ_MIHOMO retryDelay from fixed 2000ms to exponential backoff
  (200ms → 400ms → 800ms, cap 3s) so core-dependent queries retry faster
- Expose isCoreDataPending from AppDataProvider to distinguish between
  data still loading vs actual errors
- ClashModeCard: show placeholder instead of "communication error" while
  core data is pending
- CurrentProxyCard: show empty space instead of "no active node" while
  core data is pending

src/components/home/clash-mode-card.tsx

@@ -41,7 +41,7 @@ const MODE_META: Record<
 export const ClashModeCard = () => {
   const { t } = useTranslation()
   const { verge } = useVerge()
-  const { clashConfig, refreshClashConfig } = useAppData()
+  const { clashConfig, isCoreDataPending, refreshClashConfig } = useAppData()
 
   // 支持的模式列表
   const modeList = CLASH_MODES
@@ -57,8 +57,11 @@ export const ClashModeCard = () => {
     if (currentModeKey) {
       return t(MODE_META[currentModeKey].description)
     }
+    if (isCoreDataPending) {
+      return '\u00A0'
+    }
     return t('home.components.clashMode.errors.communication')
-  }, [currentModeKey, t])
+  }, [currentModeKey, isCoreDataPending, t])
 
   // 模式图标映射
   const modeIcons = useMemo(

src/components/home/current-proxy-card.tsx

@@ -105,7 +105,8 @@ export const CurrentProxyCard = () => {
   const { t } = useTranslation()
   const navigate = useNavigate()
   const theme = useTheme()
-  const { proxies, clashConfig, refreshProxy, rules } = useAppData()
+  const { proxies, clashConfig, isCoreDataPending, refreshProxy, rules } =
+    useAppData()
   const { verge } = useVerge()
   const { current: currentProfile } = useProfiles()
   const autoDelayEnabled = verge?.enable_auto_delay_detection ?? false
@@ -911,7 +912,9 @@ export const CurrentProxyCard = () => {
         </Box>
       }
     >
-      {currentProxy ? (
+      {isCoreDataPending ? (
+        <Box sx={{ py: 4 }} />
+      ) : currentProxy ? (
         <Box>
           {/* 代理节点信息显示 */}
           <Box