Convert Stage class from JavaScript to TypeScript (#1371)

* Convert Stage class from JavaScript to TypeScript

- Add proper type annotations for all properties, methods, and parameters
- Type onResetEvent/onDestroyEvent with Application parameter
- Fix light.update()/preDraw()/draw()/postDraw() calls to match actual signatures
  (previously passing unused extra arguments silently ignored by JS)
- Add StageSettings interface for constructor options
- Update all import paths from stage.js to stage.ts
- Add Stage unit tests (constructor, settings callbacks, update return value)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Update state.ts documentation to use modern import-based API

- Replace me.state/me.Stage/me.GUI_Object with direct imports in examples
- Update state.change() example to include forceChange parameter
- Use const instead of let in USER constant example
- Remove unused Color import

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Fix lint errors and address PR review comments

- Fix boolean comparisons: use direct truthiness instead of === true/false
- Fix arrow-body-style in tests (block statements for arrow functions)
- Use import type for Stage in event.ts (type-only usage)
- Make app parameter required in onResetEvent/onDestroyEvent signatures
- Type StageSettings.onResetEvent with explicit Application parameter
- Fix typos: renderered → rendered, Renderering → Rendering, reseting → resetting
- Update lights example to use modern import style
- Remove unused Container import comment

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: obiot

packages/melonjs/src/index.ts

@@ -43,7 +43,7 @@ import Trigger from "./renderable/trigger.js";
 import UIBaseElement from "./renderable/ui/uibaseelement.ts";
 import UISpriteElement from "./renderable/ui/uispriteelement.ts";
 import UITextButton from "./renderable/ui/uitextbutton.ts";
-import Stage from "./state/stage.js";
+import Stage from "./state/stage.ts";
 import state from "./state/state.ts";
 import { boot } from "./system/bootstrap.ts";
 import { DOMContentLoaded } from "./system/dom.ts";

packages/melonjs/src/loader/loadingscreen.js

@@ -1,6 +1,6 @@
 import Renderable from "./../renderable/renderable.js";
 import Sprite from "./../renderable/sprite.js";
-import Stage from "./../state/stage.js";
+import Stage from "./../state/stage.ts";
 import {
 	LOADER_COMPLETE,
 	LOADER_PROGRESS,