fix(10-04): prettier format + remove unnecessary type assertions

- Run prettier on all new/modified PWA files (CredentialSheet, SetupBanner, AdminPage, admin.spec.ts)
- Remove unnecessary 'as React.RefObject<HTMLElement | null>' casts flagged by @typescript-eslint/no-unnecessary-type-assertion
- Format pre-existing API files from Plans 02/03 (me.ts, user.test.ts, requireAdmin.test.ts, me.test.ts)
- All 270 API tests + 191 PWA vitest tests pass; lint/typecheck/build clean

apps/pwa/src/components/CredentialSheet.tsx

@@ -296,7 +296,9 @@ export function CredentialSheet({
           id="credential-helper"
           style={{
             fontSize: 'var(--text-label-size, 13px)',
-            color: validationError ? 'var(--color-destructive, #DC2626)' : 'var(--color-text-secondary)',
+            color: validationError
+              ? 'var(--color-destructive, #DC2626)'
+              : 'var(--color-text-secondary)',
             lineHeight: 1.4,
             marginBottom: 'var(--space-6, 24px)',
             display: 'flex',