feat(ui): lobby site-style sidebar + profile screen (#47)

- Wrap lobby and profile in a shared `lobby-shell.svelte` chrome:
  page-list sidebar (Overview/Profile) and a top "Player-xxxx"
  identity strip mirroring the project site's monospace look.
- Strip the legacy `lobby.title`, device-session-id `<code>`, and
  `lobby.greeting` paragraph; the identity strip both names the user
  and opens the profile editor.
- Add a top-level `profile` AppScreen with a three-field form
  (`display_name`, `preferred_language`, `time_zone`) backed by a new
  `src/api/account.ts` wrapper around `user.account.get`,
  `user.profile.update`, and `user.settings.update`. Saving switches
  the active i18n locale in-place when the new preferred language is
  one the UI ships translations for.
- Update e2e fixture + auth-flow / lobby-flow specs to use the new
  `lobby-account-name` testid and wait for the loaded identity before
  releasing pending `SubscribeEvents` (webkit revocation race). New
  `profile-screen.spec.ts` covers navigation, edit-save, and cancel.
- Sync `ui/docs/lobby.md` and `ui/docs/navigation.md` to the new
  layout.

Closes #47

ui/frontend/src/lib/i18n/locales/en.ts

@@ -50,11 +50,11 @@ const en = {
 	"login.device_key_not_ready":
 		"device key is not ready, please reload the page",
 
-	"lobby.title": "you are logged in",
-	"lobby.device_session_id_label": "device session id",
-	"lobby.greeting": "hello, {name}!",
 	"lobby.account_loading": "loading account…",
 	"lobby.logout": "logout",
+	"lobby.nav.aria_label": "lobby pages",
+	"lobby.nav.overview": "Overview",
+	"lobby.nav.profile": "Profile",
 	"lobby.section.my_games": "my games",
 	"lobby.section.invitations": "pending invitations",
 	"lobby.section.applications": "my applications",
@@ -103,6 +103,21 @@ const en = {
 	"lobby.error.internal_error": "internal server error",
 	"lobby.error.unknown": "{message}",
 
+	"profile.title": "Profile",
+	"profile.loading": "loading account…",
+	"profile.field.user_name": "username",
+	"profile.field.email": "email",
+	"profile.field.display_name": "display name",
+	"profile.field.preferred_language": "preferred language",
+	"profile.field.time_zone": "time zone",
+	"profile.hint.display_name": "shown wherever Galaxy needs a friendlier name than the username handle. Leave empty to fall back to the username.",
+	"profile.hint.time_zone": "IANA time-zone name (e.g. Europe/Moscow, America/New_York). The placeholder shows your browser's current zone.",
+	"profile.save": "save",
+	"profile.saving": "saving…",
+	"profile.cancel": "cancel",
+	"profile.error.language_required": "language must not be empty",
+	"profile.error.time_zone_required": "time zone must not be empty",
+
 	"game.shell.unknown": "?",
 	"game.shell.connection.online": "online",
 	"game.shell.connection.reconnecting": "reconnecting…",