[Integration] Convert Vuetify to use @vuetify/0 useDate

[johnleider]

Summary

Convert Vuetify 3 to use @vuetify/v0 useDate.

Research Findings

Major Consideration: Ecosystem Change

Vuetify 3 uses date-io ecosystem (dayjs, luxon, date-fns, moment adapters).
v0 uses Temporal API with @js-temporal/polyfill.

This is the most significant integration challenge.

Options

Option A: Keep Temporal, Create Adapters

• Build @vuetify/v0-date-dayjs, @vuetify/v0-date-luxon, etc.
• These wrap Temporal internally but accept library-specific input
• Maintains v0's richer API (62 methods vs 52)

Option B: Create Bridge Package

• @vuetify/v0-date-io that wraps date-io adapters
• Loses some v0 methods but gains ecosystem compatibility
• Less work for existing Vuetify 3 users

Option C: Gradual Migration

• Vuetify 3 can use both date systems during transition
• v0 for new features, date-io for existing components
• Eventually consolidate

Recommendation

Option A - Create v0-native adapters for popular libraries. This:

• Maintains v0's SSR safety and Intl-first approach
• Provides ecosystem flexibility
• Keeps the richer API surface

v0 API Advantages Worth Preserving

• addSeconds(), addYears() - More complete arithmetic
• isAfterMonth(), isBeforeDay() - Granular comparisons
• getDaysInMonth(), getMonthArray() - Calendar helpers
• formatByString() - Token-based formatting
• Auto locale sync with useLocale()

Dependencies

• [Audit] useDate - ensure adapter system matches Vuetify #106 - Audit useDate adapter system

Tasks

• Decide on integration strategy (A, B, or C)
• Create first adapter package (recommend dayjs)
• Test with VDatePicker, VTimePicker components
• Document migration path from date-io
• Benchmark Temporal vs native Date performance