feat(editor): scaffold editor package

UI-only feature package for the ADR-029 editor rebuild: tsconfig
rootDir '.', vitest jsdom base with '@' alias and honest L0 baseline
thresholds, conformance ESLint active, React 19, @xyflow/react +
zustand wired against the pre-approved 2026-07-12 library traces.
Minimal feature.manifest.ts (empty useCases — no binders; declares
requiredCores runner-protocol + baseline coverage band) so the editor
participates in pnpm conformance without weakening any lint rule.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016j8z4VHjedXDTjEDNg7qHK

packages/editor/package.json

@@ -0,0 +1,40 @@
+{
+  "name": "@repo/editor",
+  "private": true,
+  "version": "0.1.0",
+  "type": "module",
+  "exports": {
+    ".": "./src/index.ts",
+    "./ui": "./src/ui/index.ts"
+  },
+  "scripts": {
+    "build": "tsc --noEmit",
+    "lint": "eslint .",
+    "test": "vitest run --passWithNoTests",
+    "typecheck": "tsc --noEmit"
+  },
+  "dependencies": {
+    "@repo/core-runner-protocol": "workspace:*",
+    "@repo/core-shared": "workspace:*",
+    "@xyflow/react": "^12.0.0",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
+    "zod": "^3.24.0",
+    "zustand": "^5.0.0"
+  },
+  "devDependencies": {
+    "@repo/core-eslint": "workspace:*",
+    "@repo/core-testing": "workspace:*",
+    "@repo/core-typescript": "workspace:*",
+    "@storybook/react": "^8.6.0",
+    "@testing-library/jest-dom": "^6.5.0",
+    "@testing-library/react": "^16.0.0",
+    "@testing-library/user-event": "^14.5.0",
+    "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
+    "@vitest/coverage-v8": "^3.2.4",
+    "jsdom": "^25.0.0",
+    "typescript": "^5.8.0",
+    "vitest": "^3.0.0"
+  }
+}