fix(date-field): flag typed/shortcut input invalid when outside min/max or unavailable

[interacsean]

Summary

Fixes a pre-existing bug (spotted in the vite example's "Future dates only" DatePicker): a date entered by typing — or landed via a keyboard shortcut — outside the allowed range was silently accepted. minValue/maxValue were only consulted by the shortcut clamp, and isDateUnavailable only gated calendar selection; the typed value had no validation at all.

The field now flags such a value invalid (aria-invalid on the segments + a built-in message) while still emitting it through onChange — matching how the calendar already behaves and Adobe React ARIA's validation contract (which flags invalid rather than clamping text entry).

This is independent of the DateRangePicker work in #388 — it lives in the shared field engine (use-date-field-state.ts) and back-fixes DateField and DatePicker. The DateRangePicker inherits the same hook and will get a small wiring commit on #388.

Changes

• applyShortcut no longer clamps. A shortcut target (e.g. y → 1 Jan) outside [minValue, maxValue] is now surfaced as invalid instead of being coerced to the boundary — consistent with typing. The open-popover (calendar) path still clamps roving focus, since you can't type there.
• isDateUnavailable drives field validation (both DateField and DatePicker), not just calendar selection — so weekends or specific blackout dates typed into the field are flagged too.
• useDateFieldState returns { isInvalid, invalidReason } (range vs unavailable). date-field.tsx ORs it into the derived invalid state and shows a localized default message (en/ja) that a consumer errorMessage overrides.
• The value still flows through onChange — we flag, we don't block or clamp — so forms can decide what to do with it.

Testing

• pnpm --filter @tailor-platform/app-shell test — 1354 passing. New/updated coverage in date-field.test.tsx:
  • typed date before minValue → invalid + still emits (with the built-in message)
  • invalid flag clears once the typed date returns to range
  • typed unavailable date (isDateUnavailable) → invalid
  • applyShortcut out of [min,max] → invalid, not clamped (DateField + DatePicker); the open-popover shortcut still clamps roving focus (unchanged)
• pnpm type-check (9/9) and pnpm lint clean.

Note: keyboard-driven manual repro isn't feasible through the preview harness (the iframe won't hold focus for synthetic key events), so the behavior is verified by the RTL suite above, which drives the real key handlers via userEvent.keyboard.

Follow-up

Once this merges, #388 rebases onto it and gains a two-line wiring (pass isDateUnavailable to each end's field state + OR isInvalid into the range picker's derived invalid state) so the range picker's typed ends validate the same way.

🤖 Generated with Claude Code

[IzumiSy]

/review

[github-actions]

✅ API Design Review completed successfully!

API design review complete for PR #390 — no issues found. Approved. Changes fix date validation for typed/shortcut input, correctly wire isDateUnavailable to field state, and keep new types (DateFieldInvalidReason) internal. No breaking public API surface changes.