feat: react 19 support and new onShow and onHide triggers

[Aerilym]

• React 19 support
• Deprecated Menu onVisibilityChange
• Added new callbacks to Menu onShow and onHide

Back-ported PRs and Issues from origin:

• upgrade: react version upgraded to react 19 fkhadra/react-contexify#276
• JSX compilation may not be compatible with React 19 fkhadra/react-contexify#269
• onShown and onHidden continue appearing in the doc after been removed fkhadra/react-contexify#252

[Copilot]

Pull request overview

Adds React 19-related updates and introduces new Menu visibility callbacks (onShow/onHide) while deprecating onVisibilityChange.

Changes:

• Updated React type dependencies (and related lockfile entries) toward React 19.
• Added onShow(fromHidden) and onHide() to Menu, and marked onVisibilityChange as deprecated.
• Updated build config to externalize React runtime packages.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
yarn.lock	Updates resolved dependency graph for React 19 types and related packages.
tsup.config.ts	Marks react, react-dom, and react/jsx-runtime as externals for bundling.
src/components/Menu.tsx	Adds onShow/onHide, deprecates onVisibilityChange, and adds ref plumbing.
src/components/Item.tsx	Initializes useRef with null (typing/runtime alignment).
package.json	Updates peer/dev dependency declarations to React 19 types and adjusts React peer range.

Comments suppressed due to low confidence (1)

package.json:79

• Removing react/react-dom from root devDependencies will break the repo’s example app and CI: example/package.json aliases react and react-dom to ../node_modules/*, and the GitHub Action starts the example via yarn start. Re-add react/react-dom as devDependencies (or move them into example dependencies and update the alias strategy/CI accordingly).

  "devDependencies": {
    "@types/react": "^19.2.7",
    "@types/react-dom": "^19.2.3",
    "cssnano": "^5.1.14",
    "cssnano-cli": "^1.0.5",
    "cypress": "^11.0.1",
    "postcss": "^8.4.18",
    "postcss-cli": "^10.0.0",
    "sass": "^1.56.1",
    "style2js": "^1.0.1",
    "tsup": "^6.4.0",
    "typescript": "^4.8.4"

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