[ENG-46317] feat(webkit): evolve Calendar into a date-range picker

[HerbertJulio]

Summary

Evolves the calendar component (ENG-46317) from the inline month grid into a full date-range picker (composition, spec_version 3), aligned to the Figma handoff.

A trigger opens a CSS-positioned popover (usePlacement + <Teleport>, no positioning lib) containing:

• one or more month grids — single / range, multi-month, connected range band
• Start/End date + time fields (12-hour)
• a timezone selector (Local (UTC ±hh:mm (ABBR)), derived via Intl)
• a full-width Apply Range action — staged-apply: edits a draft inside the popover and commits to v-model only on Apply (or immediately when show-apply is false)
• a presets rail and a Select Period relative-time mode that parses spans like 45m, last month, 1/1 - 1/2
• a clearable / split trigger, small | medium | large sizes, and a horizontal layout

Public import stays @aziontech/webkit/calendar (compound API with Calendar.Preset / Calendar.Clear); standalone calendar-root, calendar-preset, calendar-clear exports were added for tree-shaking.

Date math uses native Date + Intl only — no date or positioning libraries.

Notes

• Verified locally: vue-tsc type-check, eslint (--max-warnings 0), type-coverage (99.96%), and storybook:build — all green.
• Timezone is a display/formatting label only; the picker does not re-interpret Date objects across zones (native-Date timezone arithmetic is intentionally avoided per the no-date-library rule).
• Possible breaking change: the @aziontech/webkit/calendar public surface changed from the always-inline grid to the picker (new props, mode now defaults to range). Left as feat (minor) for now — flag if a major bump is preferred and I'll add the ! + BREAKING CHANGE footer.
• Related issue: ENG-46317.