fix(device): restore me.device.{requestFullscreen,exitFullscreen} re-export

Reverts the unintended removal of the device-namespace aliases from
fd0fc67. Per the user clarification: implementations stay in
`lang/deprecated.js` (correct — that's where the engine's other
deprecation surface lives) but the names need to be reachable as
`me.device.requestFullscreen` / `me.device.exitFullscreen` for
backwards compatibility with consumers still calling through that
namespace.

Net structure:
- `lang/deprecated.js` — function bodies + `warning(...)` runtime
  call + the four-variant vendor probe
- `system/device.ts` — one re-export line so the names appear on
  `me.device.*`. eslint-disable on the re-export covers the
  `no-deprecated` rule (which fires when re-exporting deprecated
  symbols — intentional here, since the whole point is to surface
  them under the deprecated alias)
- `system/fullscreen.ts` — `hasFullscreenSupport` / `isFullscreen`
  (canonical, non-deprecated), imported by BOTH device.ts and
  lang/deprecated.js. No circular dep.

Verified round-trip via Playwright keypress on the platformer
example — still req:1 / exit:1 end-to-end through the four-variant
probe, zero page errors.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: obiot

packages/melonjs/src/system/device.ts

@@ -404,12 +404,15 @@ export function enableSwipe(enable?: boolean) {
 	}
 }
 
-// `requestFullscreen` / `exitFullscreen` were removed from `me.device.*` in
-// 19.7.0 — the implementations live in `lang/deprecated.js` and surface at
-// the top level via `index.ts`'s `export * from "./lang/deprecated.js"`,
-// so `me.requestFullscreen()` keeps working as a top-level deprecated shim
-// with the canonical migration target being `Application#requestFullscreen` /
-// `Application#exitFullscreen`.
+// `requestFullscreen` / `exitFullscreen` were deprecated in 19.7.0 — the
+// implementations live with the rest of the engine's deprecation surface in
+// `lang/deprecated.js`. Re-exported here so they stay reachable as
+// `me.device.requestFullscreen` / `me.device.exitFullscreen` for backwards
+// compat; the disable below covers the re-export of `@deprecated` symbols
+// (the whole point — consumers still get the JSDoc + runtime warning when
+// they call them).
+// eslint-disable-next-line @typescript-eslint/no-deprecated
+export { exitFullscreen, requestFullscreen } from "../lang/deprecated.js";
 
 /**
  * Return a string representing the orientation of the device screen.