fix: Submenu active state + currency symbols + flags integration

1. Fixed Submenu Active State ✅
   Problem: First submenu always active due to pathname.startsWith()
   - /dashboard matches /dashboard/analytics
   - Both items show as active

   Solution: Use exact match instead
   - const isActive = pathname === it.path
   - Only clicked item shows as active

   Files: DashboardSubmenuBar.tsx, SubmenuBar.tsx

2. Fixed Currency Symbol Display ✅
   Problem: HTML entities showing (ءإ)
   Solution: Use currency code when symbol has HTML entities

   Before: United Arab Emirates dirham (ءإ)
   After: United Arab Emirates dirham (AED)

   Logic:
   const displaySymbol = (!currency.symbol || currency.symbol.includes('&#'))
     ? currency.code
     : currency.symbol;

3. Integrated Flags.json ✅

   A. Moved flags.json to admin-spa/src/data/
   B. Added flag support to SearchableSelect component
      - New icon prop in Option interface
      - Displays flag before label in trigger
      - Displays flag before label in dropdown

   C. Currency select now shows flags
      - Flag icon next to each currency
      - Visual country identification
      - Better UX for currency selection

   D. Dynamic store summary with flag
      Before: 🇮🇩 Your store is located in Indonesia
      After: [FLAG] Your store is located in Indonesia

      - Flag based on selected currency
      - Country name from flags.json
      - Currency name (not just code)
      - Dynamic updates when currency changes

Benefits:
✅ Clear submenu navigation
✅ Readable currency symbols
✅ Visual country flags
✅ Better currency selection UX
✅ Dynamic store location display

Files Modified:
- DashboardSubmenuBar.tsx: Exact match for active state
- SubmenuBar.tsx: Exact match for active state
- Store.tsx: Currency symbol fix + flags integration
- searchable-select.tsx: Icon support
- flags.json: Moved to admin-spa/src/data/

admin-spa/src/routes/Settings/components/SettingsLayout.tsx

@@ -38,7 +38,7 @@ export function SettingsLayout({
       {/* Sticky Header with Save Button */}
       {onSave && (
         <div className="sticky top-0 z-10 border-b bg-background/95 backdrop-blur supports-[backdrop-filter]:bg-background/60">
-          <div className="container max-w-5xl mx-auto px-4 py-3 flex items-center justify-between">
+          <div className="container px-0 max-w-5xl mx-auto py-3 flex items-center justify-between">
             <div>
               <h1 className="text-lg font-semibold">{title}</h1>
             </div>
@@ -61,7 +61,7 @@ export function SettingsLayout({
       )}
 
       {/* Content */}
-      <div className="container max-w-5xl mx-auto px-4 py-8">
+      <div className="container px-0 max-w-5xl mx-auto">
         {!onSave && (
           <div className="mb-8">
             <div className="flex items-start justify-between gap-4">