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/Payments.tsx

@@ -336,16 +336,6 @@ export default function PaymentsPage() {
             </div>
             {/* Footer outside scrollable area */}
             <div className="border-t px-4 py-3 flex flex-col gap-2 shrink-0 bg-background">
-              <Button 
-                onClick={() => {
-                  const form = document.querySelector('form');
-                  if (form) form.requestSubmit();
-                }}
-                disabled={saveMutation.isPending}
-                className="w-full"
-              >
-                {saveMutation.isPending ? 'Saving...' : 'Save Settings'}
-              </Button>
               <Button
                 type="button"
                 variant="ghost"
@@ -362,6 +352,16 @@ export default function PaymentsPage() {
                   <ExternalLink className="h-4 w-4" />
                 </a>
               </Button>
+              <Button 
+                onClick={() => {
+                  const form = document.querySelector('form');
+                  if (form) form.requestSubmit();
+                }}
+                disabled={saveMutation.isPending}
+                className="w-full"
+              >
+                {saveMutation.isPending ? 'Saving...' : 'Save Settings'}
+              </Button>
               <Button
                 type="button"
                 variant="outline"