fix(frontend): post-QA sprint 2 — i18n + alignment + textarea + action bar layout

- Translate all remaining French strings to English (toasts, buttons, banner)
- Fix UsersAdminPage create-form grid alignment: items-start + self-end on button wrapper
- Change execution_result from TextInput to TextArea (5 rows, multiline)
- Replace split Save RT / Save SOC footers + workflow div with a single sticky
  action bar (Save Red Team | Save SOC | Mark for review | Close | Delete)
- Update Vitest assertions to use English button labels

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/UsersAdminPage.tsx

@@ -110,7 +110,7 @@ export function UsersAdminPage(): JSX.Element {
 
       <section className="card-product flex flex-col gap-md">
         <h2 className="text-[20px] font-medium">Create account</h2>
-        <form onSubmit={onCreate} className="grid grid-cols-1 md:grid-cols-4 gap-md items-end">
+        <form onSubmit={onCreate} className="grid grid-cols-1 md:grid-cols-4 gap-md items-start">
           <FormField label="Username" htmlFor="new-username" required>
             <TextInput
               id="new-username"
@@ -137,9 +137,11 @@ export function UsersAdminPage(): JSX.Element {
               options={ROLE_OPTIONS}
             />
           </FormField>
-          <button type="submit" className="btn-primary" disabled={createMutation.isPending}>
-            {createMutation.isPending ? 'Creating…' : 'Create'}
-          </button>
+          <div className="self-end">
+            <button type="submit" className="btn-primary w-full" disabled={createMutation.isPending}>
+              {createMutation.isPending ? 'Creating…' : 'Create'}
+            </button>
+          </div>
         </form>
         {createError ? (
           <div role="alert" className="text-[14px] text-bloom-deep">