Add i18n factory + AdminShell My Profile + LogoutButton anchor

- src/i18n/server.ts: createI18nConfig factory consolidating the locale
  resolution chain (cookie → access_token preferred_language claim →
  Accept-Language → default). Reusable across apps; previously each
  frontend reimplemented it.
- AdminShell: thread signoutPath + myProfileUrl (default
  https://my.gosec.internal/profile) into the navbar; render My Profile
  link alongside logout.
- LogoutButton: replace two-step fetch+signOut+redirect with a plain
  anchor pointing at signoutPath — the NextAuth POST-only signout
  endpoint plus form-CSRF flow doesn't need client JS.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/chrome/labels.ts

@@ -15,6 +15,7 @@ export const DEFAULT_CHROME_LABELS: ChromeLabels = {
   settings: "Settings",
   allSettings: "All Settings",
   logout: "Logout",
+  myProfile: "My Profile",
   docs: "Docs",
   browseApps: "Browse apps",
   viewAll: "View all",