feat(2d): support pixelsToUnit in SpriteFrame.reset

[shrinktofit]

Re: #

This gives callers an opportunity to set pixels per unit when initializing a SpriteFrame through reset(), for example when creating sprite frames directly in tests. Unity's Sprite.Create similarly accepts a pixelsPerUnit argument at sprite creation time.

Changelog

• Support setting pixelsToUnit through SpriteFrame.reset().

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Continuous Integration

This pull request:

• needs automatic test cases check.

  Manual trigger with @cocos-robot run test cases afterward.

• does not change any runtime related code or build configuration

  If any reviewer thinks the CI checks are needed, please uncheck this option, then close and reopen the issue.

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Compatibility Check

This pull request:

• changes public API, and have ensured backward compatibility with deprecated features.
• affects platform compatibility, e.g. system version, browser version, platform sdk version, platform toolchain, language version, hardware compatibility etc.
• affects file structure of the build package or build configuration which requires user project upgrade.
• introduces breaking changes, please list all changes, affected features and the scope of violation.

[shrinktofit]

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[github-actions]

Code Size Check Report

Wechat (WASM)	Before	After	Diff
2D Empty (legacy pipeline)	1014446 bytes	1014590 bytes	⚠️ +144 bytes
2D All (legacy pipeline)	2681971 bytes	2682115 bytes	⚠️ +144 bytes
2D All (new pipeline)	2773763 bytes	2773907 bytes	⚠️ +144 bytes
(2D + 3D) All	10031072 bytes	10031216 bytes	⚠️ +144 bytes

Web (WASM + ASMJS)	Before	After	Diff
(2D + 3D) All	16867485 bytes	16867629 bytes	⚠️ +144 bytes

Interface Check Report

! WARNING this pull request has changed these public interfaces:

@@ -732,8 +732,14 @@
          * 在图集中的精灵帧可能会被剔除透明像素以获得更高的空间利用李，剔除后的矩形尺寸比剪裁前更小，偏移量指的是从原始矩形的中心到剪裁后的矩形中心的距离。
          */
         offset?: math.Vec2;
         /**
+         * @en Number of pixels corresponding to unit size in world space.
+         * @zh 世界空间中的单位大小对应的像素数量。
+         * @default 100
+         */
+        pixelsToUnit?: number;
+        /**
          * @en Top side border for sliced 9 frame.
          * @zh 九宫格精灵帧的上边界。
          * @default 0
          */
@@ -1156,9 +1162,9 @@
          * @en clone a sprite frame.
          * @zh 克隆当前 sprite frame。
          */
         clone(): SpriteFrame;
-        protected _refreshTexture(texture: __private._cocos_asset_assets_texture_base__TextureBase): void;
+        protected _refreshTexture(texture: __private._cocos_asset_assets_texture_base__TextureBase, updateMesh?: boolean): void;
         /**
          * @en complete loading callback.
          * @zh 加载完成回调。
          * @deprecated since v3.7.0, this is an engine private interface that will be removed in the future.