feat(Collapse): create CollapseDelayed variant

[robertpenner]

Previous Behavior

• Collapse animates size (height or width) and opacity in sync: they start together and have the same duration.

New Behavior

• CollapseDelayed is a new variant that animates size and opacity separately:
  • Enter: size expands immediately, while the fade-in starts after a delay.
  • Exit: fade-out first, then size collapses after a delay.

Documentation

• Added a CollapseDelayed example in Storybook.

Refactoring

• Extracted Collapse motion atom objects to reusable factory functions and moved them to a separate file.
• Moved Collapse types to a separate file as well.

Related Issue(s)

• Fixes [Collapse] add delayed variant #33068

[fabricteam]

📊 Bundle size report

Package & Exports	Baseline (minified/GZIP)	PR	Change
react-accordion Accordion (including children components)	105.317 kB 32.37 kB	106.678 kB 32.689 kB	1.361 kB 319 B
react-components react-components: Accordion, Button, FluentProvider, Image, Menu, Popover	219.108 kB 63.51 kB	220.469 kB 63.821 kB	1.361 kB 311 B
react-components react-components: entire library	1.157 MB 289.896 kB	1.159 MB 290.234 kB	1.361 kB 338 B

Unchanged fixtures

Package & Exports	Size (minified/GZIP)
react-components react-components: Button, FluentProvider & webLightTheme	69.14 kB 20.137 kB
react-components react-components: FluentProvider & webLightTheme	44.447 kB 14.59 kB
react-portal-compat PortalCompatProvider	8.39 kB 2.64 kB
react-timepicker-compat TimePicker	107.387 kB 35.758 kB

_{🤖 This report was generated against 54a28ec2c872c9cbcb3a05204568510429cf0031}

[fabricteam]

Perf Analysis (@fluentui/react-components)

No significant results to display.

All results

Scenario	Render type	Master Ticks	PR Ticks	Iterations	Status
Avatar	mount	664	615	5000
Button	mount	300	295	5000
Field	mount	1119	1117	5000
FluentProvider	mount	719	737	5000
FluentProviderWithTheme	mount	88	76	10
FluentProviderWithTheme	virtual-rerender	32	38	10
FluentProviderWithTheme	virtual-rerender-with-unmount	73	72	10
MakeStyles	mount	875	871	50000
Persona	mount	1773	1740	5000
SpinButton	mount	1378	1376	5000
SwatchPicker	mount	1684	1671	5000

[robertpenner]

/azp run license/cla

[azure-pipelines]

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[robertpenner]

/azp run

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