style: format frontend, docs and skills with prettier; add .prettierignore

One-time prettier --write so the new format:check CI gate starts green.
.prettierignore excludes generated (api-client.ts, documentation.json),
vendored (public/cibg-huisstijl), and backend (dotnet format owns it).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/shared/application/submit.ts

@@ -7,7 +7,10 @@ import { problemDetail } from '@shared/infrastructure/api-error';
  * its own payload mapping. The backend re-validates and returns a 422
  * ProblemDetails on rejection, surfaced here as the error string.
  */
-export async function runSubmit<T>(fn: () => Promise<T>, fallback: string): Promise<Result<string, T>> {
+export async function runSubmit<T>(
+  fn: () => Promise<T>,
+  fallback: string,
+): Promise<Result<string, T>> {
   try {
     return ok(await fn());
   } catch (e) {