fix(StorageCleaner, Base64Converter): fix layout padding and checkbox alignment

- StorageCleaner: add px-3.5 to grid container to prevent content sticking to border
- StorageCleaner: adjust select-all bar to pl-3.5 pr-7 for checkbox alignment with grid items
- Base64Converter: add px-2 to TextMode and Base64ConverterSection for consistent spacing

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/pages/Base64Converter/Base64ConverterSection.tsx

@@ -57,7 +57,7 @@ export default function Base64ConverterSection({ mode }: Base64ConverterSectionP
   };
 
   return (
-    <div className="w-full flex flex-col space-y-4">
+    <div className="w-full flex flex-col space-y-4 px-2">
       <div className="flex h-11 items-center px-1.5 bg-secondary/40 rounded-xl border border-border/60 w-fit">
         <SwitchButtonGroup
           value={direction}

src/pages/Base64Converter/TextMode.tsx

@@ -88,7 +88,7 @@ export default function TextMode({ onSwitchToImageMode }: TextModeProps = {}) {
   };
 
   return (
-    <div className="w-full flex flex-col space-y-4">
+    <div className="w-full flex flex-col space-y-4 px-2">
       {/* 受控方向切流中枢 */}
       <div className="flex h-11 items-center px-1.5 bg-secondary/40 rounded-xl border border-border/60 w-fit">
         <SwitchButtonGroup

src/pages/StorageCleaner/StorageOptionsGrid.tsx

@@ -42,7 +42,7 @@ export default function StorageOptionsGrid({
 
   return (
     <div className={cn('w-full overflow-hidden', className)} {...props}>
-      <div className="px-0 pt-3.5 pb-2">
+      <div className="px-3.5 pt-3.5 pb-2">
         <div className="grid grid-cols-2 gap-2 items-stretch">
           {optionKeys.map(({ key, isCount }) => (
             <OptionItem
@@ -59,7 +59,7 @@ export default function StorageOptionsGrid({
 
       <div
         onClick={handleToggleAll}
-        className="border-t border-border flex justify-between items-center px-3.5 py-2.5 bg-muted/20 hover:bg-muted/40 cursor-pointer select-none transition-colors"
+        className="border-t border-border flex justify-between items-center pl-3.5 pr-7 py-2.5 bg-muted/20 hover:bg-muted/40 cursor-pointer select-none transition-colors"
       >
         <Label className="text-xs font-bold text-muted-foreground/90 cursor-pointer tracking-wide uppercase">
           {t('storageCleaner:selectAll')}