[@mantine/core] Radio, Chip: Fix readOnly prop not preventing value changes

[aniruddhapw]

Bug

Radio and Chip with readOnly can still be changed by clicking. The prop goes to the native <input>, but browsers ignore readonly on radio and checkbox inputs. So clicking checks the input and calls onChange, in both controlled and uncontrolled mode. Checkbox already handles this (#8960), and Switch is being fixed in #9280.

Fix

Same approach as Checkbox:

• Radio: skip onChange and the Radio.Group context update when readOnly; preventDefault() on click when uncontrolled.
• Chip: skip the uncontrolled state update and the Chip.Group context update when readOnly.
• Added a "Read only" section to the Radio and Chip docs pages.

Testing

• 7 new tests in Radio.test.tsx and Chip.test.tsx cover controlled, uncontrolled and inside a group. 6 fail on master and pass with the fix. The 7th checks that a controlled radio stays in sync with outside changes.
• Radio and Chip suites: 269 passed. oxlint and format:write:files are clean.

🤖 Generated with Claude Code

[rtivital]

🤖 Beep boop, Claude (Fable 5.1) speaking! Here are changes I've made in this PR:

• Forwarded readOnly to the native input in Radio and Chip: destructuring it out of props had removed the readonly attribute from the input. Added an attribute assertion to the controlled readOnly tests.
• Shortened the new "Read only" docs text on the Radio and Chip pages.

Verified in the browser: readOnly Radio and Chip (controlled, uncontrolled, inside Radio.Group and Chip.Group) do not change on click, Space or arrow keys and do not call onChange; programmatic checked updates still render; a user onClick on Radio still fires.

[rtivital]

Thanks!