fix(frontend): generic delete warning without FAC-001 reference (PRC-001)

User feedback from smoke test: the FAC-001 reference is future-coupled — when
the invoicing module lands we would need to remember to update the dialog text.
Switched to a timeless message that describes the current behavior: 'La
eliminación es posible porque este carácter no está en uso.' It stays accurate
before and after the FAC-001 usage guard ships.

src/web/src/features/chargeableChars/__tests__/DeleteChargeableCharConfigDialog.test.tsx

@@ -40,7 +40,7 @@ describe('DeleteChargeableCharConfigDialog', () => {
     await waitFor(() => expect(screen.getByRole('dialog')).toBeInTheDocument())
     expect(screen.getByText(/eliminará permanentemente/i)).toBeInTheDocument()
     expect(screen.getByText(/'\$'/)).toBeInTheDocument()
-    expect(screen.getByText(/FAC-001/i)).toBeInTheDocument()
+    expect(screen.getByText(/no está en uso/i)).toBeInTheDocument()
   })
 
   it('confirm button calls delete mutation and shows success toast', async () => {

src/web/src/features/chargeableChars/components/DeleteChargeableCharConfigDialog.tsx

@@ -63,8 +63,7 @@ export function DeleteChargeableCharConfigDialog({
         <Alert variant="destructive">
           <AlertTriangle className="h-4 w-4" />
           <AlertDescription>
-            La eliminación es posible porque aún no existe el módulo de facturación (FAC-001).
-            Cuando se active, no podrán eliminarse símbolos ya usados.
+            La eliminación es posible porque este carácter no está en uso.
           </AlertDescription>
         </Alert>