收口前端平台组件库能力

新增 PlatformUiKit 通用弹窗、按钮、状态、空态、媒体、表单和标签等公共组件
迁移结果页、创作工作台、认证入口、RPG 暗色面板和运行态弹窗的重复 UI chrome
补充组件测试、页面回归测试、技术文档和 Hermes 共享决策记录

src/components/common/squareImageCropModel.test.ts

@@ -0,0 +1,38 @@
+import { expect, test } from 'vitest';
+
+import {
+  buildCenteredSquareImageCropRect,
+  clampSquareImageCropRect,
+} from './squareImageCropModel';
+
+test('builds a centered square crop from a rectangular image', () => {
+  expect(buildCenteredSquareImageCropRect({ width: 1200, height: 800 })).toEqual({
+    x: 200,
+    y: 0,
+    size: 800,
+  });
+});
+
+test('clamps square crop size and position inside image bounds', () => {
+  expect(
+    clampSquareImageCropRect(
+      { width: 300, height: 200 },
+      { x: 260, y: -30, size: 500 },
+    ),
+  ).toEqual({
+    x: 100,
+    y: 0,
+    size: 200,
+  });
+
+  expect(
+    clampSquareImageCropRect(
+      { width: 300, height: 200 },
+      { x: 120, y: 90, size: 10 },
+    ),
+  ).toEqual({
+    x: 120,
+    y: 90,
+    size: 48,
+  });
+});