feat: add independently controlled visible months

[Albatrosso]

Summary

Adds a draft visibleMonths API for controlling displayed calendar months independently.

This is intended for range pickers where the selected from and to dates may be far apart, and the UI should show both endpoint months at the same time instead of forcing adjacent months through numberOfMonths.

What changed

• Added visibleMonths, defaultVisibleMonths, and onVisibleMonthsChange.
• Keeps the existing month / defaultMonth / numberOfMonths behavior unchanged.
• When visibleMonths is provided, displayed months come directly from that array.
• Dropdown, previous/next navigation, and keyboard navigation update the relevant visible month.
• onMonthChange is not called for visibleMonths updates.
• Allows non-chronological visible months, e.g. [Dec 2025, Jan 2024].
• Keeps range selection behavior unchanged.

Notes

This PR is intentionally narrow and focused on the core behavior/API shape. It does not add full documentation or examples yet, so naming and callback details can still be adjusted.

Validation

Ran:

pnpm exec jest --selectProjects src --runTestsByPath \
  packages/react-day-picker/src/helpers/getDates.test.ts \
  packages/react-day-picker/src/DayPicker.test.tsx \
  packages/react-day-picker/src/types/props.test.tsx

pnpm --filter react-day-picker typecheck
pnpm lint
git diff --check

[changeset-bot]

🦋 Changeset detected

Latest commit: 398f115

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 7 packages

Name	Type
react-day-picker	Minor
@daypicker/react	Minor
@daypicker/buddhist	Minor
@daypicker/ethiopic	Minor
@daypicker/hebrew	Minor
@daypicker/hijri	Minor
@daypicker/persian	Minor

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