Menu: Add extensible menu migration guidance

[ciampo]

Follow up to #79560.
See #61094, #81507, and #81564.

What?

Adds a Storybook migration guide for menus that receive items through SlotFill or another extension API, and links it from Menu's component status.

Why?

Gutenberg can bundle separate copies of @wordpress/ui into the menu owner and extension packages. Their Menu parts do not share React context, so the owner needs a compatibility layer that preserves the extension API's existing behavior.

The Options menu migration in #81564 exposed compatibility details that a simplified adapter would miss, including checked states, accessible names, links, shortcuts, icons, and custom renderers.

How?

Documents a host-owned adapter passed through ActionItem.Slot, with the slot's children callback composing the rendered items into the new menu. The guide requires an audit and public-path tests for the legacy item contract. It treats arbitrary custom renderers as a separate deprecation or release-policy decision.

It also adds the documentation changelog entry under the current unreleased section.

Testing Instructions

1. Run npm run storybook:dev.
2. Open Design System / Components / Menu / Migration Guide.
3. Confirm the guide covers package-copy context, ActionItem.Slot composition, legacy item compatibility, custom renderers, testing, and migration order.
4. Open Design System / Components / Menu and confirm the status note links to the migration guide.

Testing Instructions for Keyboard

Documentation-only change. Verify that links in the Menu status note and migration guide can be reached and activated with the keyboard.

Use of AI Tools

This PR was implemented with AI assistance in Codex and reviewed locally.

[github-actions]

Size Change: 0 B

Total Size: 7.73 MB

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[github-actions]

🤖 PR meta 🤖

📦 Bundle size

Size Change: 0 B

Total Size: 7.91 MB

_{c56ea30 Run}

⚡ Performance

Show the results

Client side metrics exclude the server response time.

front-end-block-theme

Metric	deed3ec	trunk	% Change
timeToFirstByte	50.1 ms +7.88% -9.08%	48.75 ms +12.31% -5.74%	2.77%
largestContentfulPaint	80 ms +2.5% -5%	80 ms +10% -5%	0%
lcpMinusTtfb	28.2 ms +8.87% -6.38%	27.7 ms +18.77% -6.14%	1.81%
wpBeforeTemplate	23.39 ms +14.96% -8.25%	22.3 ms +22.47% -2.74%	4.89%
wpTemplate	21.73 ms +3.5% -3.91%	22.41 ms +4.73% -7.27%	-3.03%
wpTotal	46.75 ms +5.5% -9.63%	45.41 ms +10.72% -6.19%	2.95%
wpMemoryUsage	7.54 MB +0% -0%	7.50 MB +0% -0%	0.45%
wpDbQueries	17 +0% -0%	17 +0% -0%	0%

front-end-classic-theme

Metric	deed3ec	trunk	% Change
timeToFirstByte	32.75 ms +12.52% -4.12%	32.95 ms +5.61% -6.98%	-0.61%
largestContentfulPaint	70 ms +2.86% -8.57%	70 ms +2.86% -8.57%	0%
lcpMinusTtfb	34.85 ms +8.61% -4.16%	34.6 ms +9.83% -5.2%	0.72%
wpBeforeTemplate	20.14 ms +7.55% -5.01%	19.67 ms +7.52% -8.03%	2.39%
wpTemplate	9.68 ms +7.02% -2.58%	9.61 ms +17.9% -3.75%	0.73%
wpTotal	29.94 ms +13.19% -3.77%	30.25 ms +6.28% -8.53%	-1.02%
wpMemoryUsage	5.42 MB +0% -0%	5.38 MB +0% -0%	0.65%
wpDbQueries	10 +0% -0%	10 +0% -0%	0%

media-processing

Metric	deed3ec	trunk	% Change
mediaProcessingJpeg	338.1 ms +2.73% -2.19%	335.75 ms +2.14% -2.43%	0.7%
mediaProcessingAvif	5075.63 ms +0.75% -0.42%	5078.73 ms +0.17% -0.72%	-0.06%
mediaProcessingJpegToAvif	3558.52 ms +0.5% -0.48%	3552.81 ms +0.39% -1.33%	0.16%

media-upload

Metric	deed3ec	trunk	% Change
jpegUploadProcessing	1404.67 ms +3.18% -0.74%	1406.17 ms +0.24% -0.96%	-0.11%
pngUploadProcessing	175.84 ms +25.86% -1.11%	193.29 ms +24.01% -9.11%	-9.03%
largeJpegUploadProcessing	1392.02 ms +0.76% -0.61%	1394.29 ms +0.38% -1.21%	-0.16%
multipleImageUploadProcessing	1510.28 ms +0.85% -3.17%	1485.01 ms +0.53% -1.44%	1.7%

post-editor

Metric	deed3ec	trunk	% Change
serverResponse	442.78 ms +3.13% -7.47%	413.55 ms +9.73% -1.19%	7.07%
firstPaint	269.34 ms +31.66% -26.59%	228.02 ms +8.13% -22.02%	18.12%
domContentLoaded	1271.91 ms +2.16% -0.28%	1274.47 ms +0.89% -1.47%	-0.2%
loaded	1273.22 ms +2.15% -0.29%	1275.7 ms +0.89% -1.45%	-0.19%
firstContentfulPaint	429.12 ms +2.59% -6.49%	431.05 ms +3.49% -3.75%	-0.45%
firstBlock	3401.19 ms +0.28% -1.85%	3405.62 ms +1.2% -0.97%	-0.13%
type	21.13 ms +11.12% -18.17%	19.68 ms +11.33% -13.26%	7.37%
typeWithoutInspector	20.93 ms +14.19% -16.77%	20.04 ms +4.69% -17.56%	4.44%
typeWithTopToolbar	23.11 ms +8.74% -20.68%	22.67 ms +11.2% -13.98%	1.94%
typeContainer	9.29 ms +5.92% -3.34%	8.52 ms +5.87% -4.58%	9.04%
focus	80.32 ms +11.45% -9.25%	74.96 ms +18.25% -9.89%	7.15%
firstFocus	176.76 ms +0% -0%	154.93 ms +0% -0%	14.09%
selectAll	566.53 ms +3.43% -1.41%	564.82 ms +0.4% -3.57%	0.3%
listViewOpen	63.32 ms +16.3% -2.01%	64.88 ms +8.11% -12.36%	-2.4%
inserterOpen	24.22 ms +5.41% -5.08%	23.54 ms +12.62% -7.01%	2.89%
inserterHover	3.8 ms +12.63% -11.58%	3.37 ms +8.61% -13.95%	12.76%
inserterSearch	8.74 ms +6.18% -4.92%	8.44 ms +6.64% -9.95%	3.55%
loadPatterns	640.09 ms +3% -1.64%	623.14 ms +5.04% -1.47%	2.72%
wpTotal	431.37 ms +3.27% -7.5%	402.03 ms +10% -1.15%	7.3%
wpMemoryUsage	13.13 MB +0% -0%	13.10 MB +0% -0%	0.22%
wpDbQueries	54 +0% -1.85%	54 +0% -1.85%	0%

site-editor

Metric	deed3ec	trunk	% Change
serverResponse	450.77 ms +1.96% -1.86%	457.45 ms +3.95% -9.48%	-1.46%
firstPaint	242.01 ms +16.02% -12.09%	233.98 ms +15.32% -7.27%	3.43%
domContentLoaded	1336.58 ms +1.67% -0.72%	1326.19 ms +2% -0.97%	0.78%
loaded	1337.74 ms +1.67% -0.72%	1327.38 ms +2% -0.98%	0.78%
firstContentfulPaint	419.36 ms +2.18% -1.05%	419.84 ms +6.56% -3.82%	-0.11%
firstBlock	4093.58 ms +0.6% -0.72%	4057.69 ms +1.14% -0.85%	0.88%
type	20.14 ms +11.97% -18.27%	20.33 ms +12.25% -15%	-0.93%
navigate	105.54 ms +13.81% -2.25%	110.27 ms +5.55% -7.04%	-4.29%
loadPatterns	1336.53 ms +19.96% -9.28%	1292.12 ms +7.31% -2.85%	3.44%
loadPages	1094.38 ms +3.28% -1.77%	1081.96 ms +2.81% -0.93%	1.15%
wpTotal	440.87 ms +1.94% -1.99%	447.61 ms +3.91% -9.78%	-1.51%
wpMemoryUsage	12.02 MB +0% -0%	11.99 MB +0% -0%	0.31%
wpDbQueries	43.5 +1.15% -1.15%	43 +2.33% -0%	1.16%

_{c56ea30 Run}

[ciampo]

cc @Mamaduka for an early look

[Mamaduka]

This looks like a good start! A couple of quick notes:

• It seems that the guide is promoting <ActionItem> usage; we should be clear that it's an example.
• Also plan to refactor packages/editor/src/components/preview-dropdown/index.jsx; I don't expect new challenges, but it should give us a better idea.

[ciampo]

• Also plan to refactor packages/editor/src/components/preview-dropdown/index.jsx; I don't expect new challenges, but it should give us a better idea.

Sounds like a plan! I'm also going to start refactoring a few Menu usages, let's gather more into during those refactors