feat(aria/spinbutton): Add spinbutton primitive for value selection within discrete ranges

[OmerGronich]

Feature Description

Angular Aria currently lacks a spinbutton primitive.
The APG Spinbutton Pattern defines it as an input widget that restricts its value to a set or range of discrete values.

Keyboard Interaction (per APG)

Key	Function
Up Arrow	Increases the value
Down Arrow	Decreases the value
Home	Sets value to minimum (if defined)
End	Sets value to maximum (if defined)
Page Up	Increases value by larger step (optional)
Page Down	Decreases value by larger step (optional)

Required ARIA Attributes

• role="spinbutton" on the focusable element
• aria-valuenow - Current value
• aria-valuemin / aria-valuemax - Min/max allowed values
• aria-valuetext - User-friendly string (e.g., "Monday" instead of "1")
• aria-labelledby or aria-label - Accessible name
• aria-invalid="true" - When value is outside allowed range

References

APG Specification

• Spinbutton Pattern
• Quantity Spin Button
  Example
• Toolbar Example (includes font size
  spinbutton)

React Aria Prior Art

React Aria uses spinbuttons internally for date/time segment navigation:

• TimeField
• DateField
• DateRangePicker

Implementation

Draft PR: #32663

Use Case

1. Quantity Selection - Hotel booking, shopping carts, product pages
2. Time Input - Time pickers with hours, minutes, seconds segments
3. Date Picker Components - Date range selectors using spinbuttons for date segments
4. Toolbar Controls - Font size and property controls in text editors
5. Numeric Input with Constraints - Any value selection within a min/max range