test(fig): cover field-level override protection

tests/engine/io/fig/import/field-protection.test.ts

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+import { describe, expect, test } from 'bun:test'
+
+import { protectField, type ProtectionMap } from '#core/kiwi/instance-overrides/patches'
+import { syncNodeProps } from '#core/kiwi/instance-overrides/sync'
+import { SceneGraph } from '#core/scene-graph'
+import type { Fill, Stroke } from '#core/scene-graph'
+
+function pageId(graph: SceneGraph): string {
+  return graph.getPages()[0].id
+}
+
+const redFill: Fill = {
+  type: 'SOLID',
+  color: { r: 1, g: 0, b: 0, a: 1 },
+  opacity: 1,
+  visible: true,
+  blendMode: 'NORMAL'
+}
+
+const blueFill: Fill = {
+  type: 'SOLID',
+  color: { r: 0, g: 0, b: 1, a: 1 },
+  opacity: 1,
+  visible: true,
+  blendMode: 'NORMAL'
+}
+
+const redStroke: Stroke = {
+  color: { r: 1, g: 0, b: 0, a: 1 },
+  weight: 1,
+  opacity: 1,
+  visible: true,
+  align: 'CENTER',
+  cap: 'NONE',
+  join: 'MITER',
+  dashPattern: []
+}
+
+const blueStroke: Stroke = {
+  color: { r: 0, g: 0, b: 1, a: 1 },
+  weight: 1,
+  opacity: 1,
+  visible: true,
+  align: 'CENTER',
+  cap: 'NONE',
+  join: 'MITER',
+  dashPattern: []
+}
+
+describe('fig import override field protection', () => {
+  test('protected text still inherits fills', () => {
+    const graph = new SceneGraph()
+    const source = graph.createNode('TEXT', pageId(graph), {
+      text: 'Source',
+      fills: [redFill]
+    })
+    const target = graph.createNode('TEXT', pageId(graph), {
+      text: 'Override',
+      fills: [blueFill]
+    })
+    const protections: ProtectionMap = new Map()
+    protectField(protections, target.id, 'text')
+
+    syncNodeProps(graph, source, target, protections)
+
+    const synced = graph.getNode(target.id)
+    expect(synced?.text).toBe('Override')
+    expect(synced?.fills[0]?.color).toEqual(redFill.color)
+  })
+
+  test('protected strokes still inherit visibility', () => {
+    const graph = new SceneGraph()
+    const source = graph.createNode('RECTANGLE', pageId(graph), {
+      visible: false,
+      strokes: [redStroke]
+    })
+    const target = graph.createNode('RECTANGLE', pageId(graph), {
+      visible: true,
+      strokes: [blueStroke]
+    })
+    const protections: ProtectionMap = new Map()
+    protectField(protections, target.id, 'strokes')
+
+    syncNodeProps(graph, source, target, protections)
+
+    const synced = graph.getNode(target.id)
+    expect(synced?.visible).toBe(false)
+    expect(synced?.strokes[0]?.color).toEqual(blueStroke.color)
+  })
+})