fix(core): forward rest props (data-testid) to CheckboxInput's native input

[let-sunny]

Summary

CheckboxInput accepts BaseProps — which explicitly types data-* attributes ("telemetry, testing, integration hooks") — but destructures a closed list of named props with no ...rest capture, so data-testid and every other extra attribute is silently dropped and never reaches the DOM. Button, TextInput, Selector, Slider, and Badge all forward rest props to their root/interactive element; CheckboxInput is the only one of these that doesn't. The API-Conventions wiki states data-testid should "pass through to the primary interactive element".

This is the same defect class as #1415 (Selector not forwarding extra BaseProps attributes), which was fixed in #1444 with exactly this rest-spread pattern — this PR applies that established fix to CheckboxInput.

Change

• CheckboxInput.tsx: capture ...rest in the destructure and spread it onto the native <input type="checkbox"> before the component's own named attributes, so rest can never clobber checked/disabled/type — mirroring TextInput's existing pattern.
• No doc.mjs change: docPropReferences.test.ts exempts data-testid/className/style/xstyle/ref as universal props not listed per component (verified against TextInput.doc.mjs).

Verification

• 3 new co-located tests: data-testid lands on the input; arbitrary data-* lands; rest props cannot override checked/disabled/type.
• Regression proof: with the source fix reverted, the two forwarding tests fail on pre-fix code (getByTestId finds nothing / attribute null); all 31 tests in the file pass with the fix.
• pnpm --filter @astryxdesign/core typecheck clean; eslint clean on touched files; repo pre-commit checks (sync/package-boundaries/changesets/demo-media) all pass.
• Changeset: @astryxdesign/core patch.
• Note: 4 pre-existing lines in the test file were re-wrapped by the repo's pre-commit prettier hook (formatting only, no logic change).

Repro (pre-fix, published @astryxdesign/core@0.1.3 and current main)

<CheckboxInput label="Accept terms" value={false} data-testid="accept-terms" />
// rendered tree contains no trace of data-testid; the same prop on Button/TextInput
// lands on the <button>/<input> respectively

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