fix(crazygames): guest username on logout, hide fullscreen, in-game pop-ups (#4538)

Addresses four requests from the CrazyGames platform team.
Supersedes #4520 (closed when its branch was renamed to `crazygames`).

## 1. Username reverts to guest on CrazyGames logout
When a player logged into their CrazyGames account and then logged out,
the username stayed the CrazyGames name. It now reverts to a fresh guest
(`AnonXXX`) name. A `crazyGamesLoggedIn` flag guards this so it only
fires on a real login→logout transition (not on the initial "not logged
in" state, which would otherwise wipe a stored name).

## 2. Fullscreen button hidden on CrazyGames
CrazyGames provides its own fullscreen control in the game frame, so our
in-game fullscreen button is now hidden when running on CrazyGames (and
unchanged everywhere else).

## 3. Native browser prompts → in-game pop-ups
The `showInGameConfirm()` / `showInGameAlert()` helpers (promise-based,
callable from non-Lit contexts like WebSocket/popstate handlers) drive
the existing shared `<confirm-dialog>` component, so styling stays
consistent with the rest of the app. Every native `confirm()`/`alert()`
shown **during gameplay** now uses it:
- Exit-game confirmation (right sidebar + browser-back path)
- Kick-player confirmation
- Host-left notice (dispatches leave-lobby only after dismiss,
preserving the old blocking UX)
- Connection-refused notice (also removes a stale `// TODO: make this a
modal`)

## 4. `gameplayStop` when Settings menu / pop-up is open
- The pop-up helpers report `gameplayStop()` while shown and
`gameplayStart()` on dismiss.
- Settings + Graphics Settings modals now report `gameplayStop` whenever
the menu is open — previously it only fired when the modal *also* paused
the sim (singleplayer / lobby-creator), so regular multiplayer players
never triggered it. Also fixes graphics-settings so gameplay resumes
correctly on close for those players.

## Scope
Per request, this covers **in-game dialogs only**. The main-menu native
alerts (store/checkout, account, subscriptions, friends, login) were
intentionally left as-is.

## Testing
- `tsc --noEmit`, `eslint`, and `prettier --check` all pass.
- Verified the confirm and alert pop-ups render correctly in the running
app (shared `<confirm-dialog>`, danger/warning variants), resolve their
promises, and tear down their portal.
- CrazyGames-iframe-only behaviors (username revert, `gameplayStop`,
fullscreen hiding) are verified by code inspection — they require
running inside the actual CrazyGames frame.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

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

resources/lang/en.json

@@ -402,6 +402,7 @@
   },
   "error_modal": {
     "connection_error": "Connection error!",
+    "connection_refused": "Connection refused: {reason}",
     "copied": "Copied!",
     "copy_clipboard": "Copy to clipboard",
     "crashed": "Game crashed!",