DateBox: Use UTC units to get correct date, if date is just a year string (T1323373)

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[Copilot]

Pull request overview

This PR adjusts DevExtreme DateBox/date serialization behavior to avoid incorrect day shifts when parsing year-only (and other date-only) string values, and updates the jQuery playground to reproduce the scenario.

Changes:

• Update date deserialization to construct a local date using UTC calendar units for inputs detected as having no time component.
• Minor refactors in DateBox and CalendarStrategy value syncing (no functional changes intended).
• Update the jQuery playground sample to use a dxDateBox with dateSerializationFormat: "y".

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
packages/devextreme/playground/jquery.html	Replaces the playground button with a DateBox configured to serialize/parse year-only values.
packages/devextreme/js/__internal/ui/date_box/m_date_box.strategy.calendar.ts	Refactors _updateValue() to set widget options via object form.
packages/devextreme/js/__internal/ui/date_box/date_box.base.ts	Refactors serialization/deserialization code into named locals for clarity.
packages/devextreme/js/__internal/core/utils/m_date_serialization.ts	Adds UTC-based local date construction for “no time component” parsed strings.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

packages/devextreme/js/__internal/core/utils/m_date_serialization.ts:203

• Adding createLocalDateFromUTCTimestamp to the exported dateSerialization object effectively extends the (deprecated but public) core/utils/date_serialization API surface. If this helper is only needed to implement deserializeDate and/or for unit tests, consider keeping it private (not exported) and test the behavior through deserializeDate inputs instead, to avoid committing to this as a supported API.

const dateSerialization = {
  createLocalDateFromUTCTimestamp,
  dateParser,
  deserializeDate,
  serializeDate,
  getDateSerializationFormat,
};