feat(date-picker): DateRangePicker + RangeCalendar + DataTable range filter (pp-1373)

[interacsean]

Summary

Adds the two deferred-but-designed-for range components from the DatePicker proposal — DateRangePicker and RangeCalendar — with a { start, end } range value (exported as DateRange), and wires the range picker into the DataTable date between filter.

Planning issue: https://github.com/tailor-inc/platform-planning/issues/1373 (fast-follow of #1093; builds on the keyboard-shortcuts work merged in #364).

What's included

• RangeCalendar (standalone) + DateRangePicker (segmented start/end inputs sharing one popover calendar), mirroring the Adobe React ARIA interaction spec:
  • first pick anchors the range and keeps the popover open; the highlight live-extends to the hovered/arrow-focused day; the second pick completes it and closes the popover
  • picking a day before the anchor swaps the endpoints (a calendar range is always ordered); a range typed in reverse is flagged invalid with a localized message rather than silently swapped
  • keyboard: Enter/Space anchors then commits (focus auto-advances one day after anchoring so plain arrows extend); Escape cancels an in-progress selection; contiguous-range clamping around unavailable dates
• Engine refactor: the selection-agnostic grid/focus/keyboard core is extracted into useCalendarGridState, with a selection adapter so the single-value useCalendarState and the new useRangeCalendarState share everything but their selection model. The single-date Calendar/DatePicker behavior is unchanged.
• DataTable date between filter now renders one DateRangePicker (a single shared range calendar) instead of two stacked date pickers. The committed { min, max } value shape is unchanged, so GraphQL/URL serialization and chip formatting are untouched. A reversed range can no longer be applied; switching a date filter to between seeds both bounds; a malformed URL date no longer crashes the editor.
• Docs (docs/components/date-picker.md) and a changeset (minor).
• Example: the vite-app Orders page is rebuilt as a DataTable over an async mock (useOrdersQuery, ~800 ms latency) so loading/pagination/filter behavior — including the new range filter on the Placed on date column — is demoable end to end.

Testing

• pnpm type-check — green across all 9 packages
• pnpm --filter @tailor-platform/app-shell test — 1383 passing (new suites: range-calendar.test.tsx, date-range-picker.test.tsx, plus expanded toolbar/calendar/date-field coverage)
• pnpm lint — clean
• Verified live in the vite example (two-click selection, hover preview, loading skeletons, and the between → range-calendar filter)

Notes for reviewers

• Behavior change worth a look: emptying the range in a chip editor now disables Apply (removal is the chip's ✕) rather than silently removing the filter — this closes a bug where clearing one field could delete the filter while a date was still shown.
• Scoped to a single-month calendar; a two-month pane would need Tab-containment/focus rework and isn't required by the issue.
• Findings from an adversarial self-review (focus/hover desync, reversed-range handling, unavailable-date bounds, malformed-value crash) were fixed with regression tests before this PR.

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