refactor(arc): calendar date logic unification

[GTR1701]

No description provided.

[Copilot]

Pull request overview

Refactors the Abstract Resource Calendar (ARC) feature to consolidate date/day handling by removing bespoke date utilities and switching more logic to date-fns formatting and Date objects.

Changes:

• Removed multiple ARC date utility helpers (serializeDateDay, month helpers, date-object formatting, time formatting).
• Updated calendar mappers and calendar UI to generate and consume day keys via date-fns formatting.
• Updated modal header and related unit tests to display localized, formatted dates.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
src/features/abstract-resource-calendar/utils/serialize-date-day.ts	Removed date-day serialization helper.
src/features/abstract-resource-calendar/utils/get-month-by-number-and-year.ts	Removed month-by-number/year helper.
src/features/abstract-resource-calendar/utils/get-month-by-date.ts	Removed month-by-date helper.
src/features/abstract-resource-calendar/utils/get-modal-header.ts	Formats clicked day into a localized “dd MMMM yyyy” modal header.
src/features/abstract-resource-calendar/utils/get-modal-header.test.ts	Updates expectations around the modal header’s date formatting.
src/features/abstract-resource-calendar/utils/get-events-for-day.ts	Changes API to accept Date and derives day key via date-fns.
src/features/abstract-resource-calendar/utils/format-time.ts	Removed calendar event time formatting helper.
src/features/abstract-resource-calendar/utils/format-date-object.ts	Removed date-object → day-key helper.
src/features/abstract-resource-calendar/utils/find-existing-day-swap.ts	Reworks day-key generation for looking up semester day swaps.
src/features/abstract-resource-calendar/utils/event-calendar-mapper.tsx	Updates event→day mapping to use date-fns for day keys.
src/features/abstract-resource-calendar/utils/academic-calendar-mapper.tsx	Updates semester holiday/day-swap mapping to use date-fns day keys.
src/features/abstract-resource-calendar/types/internal.ts	Removes DateObject and keeps calendar internal types focused on day keys.
src/features/abstract-resource-calendar/components/arc-internal.tsx	Refactors calendar grid generation and day selection around Date objects and date-fns.
src/features/abstract-resource-calendar/components/arc-holiday-card.tsx	Displays formatted holiday date ranges (localized).
src/features/abstract-resource-calendar/components/arc-event-card.tsx	Replaces old time formatter with direct date-fns formatting.
src/features/abstract-resource-calendar/components/arc-day-button.tsx	Refactors day button props to take a Date rather than a custom date object.
src/features/abstract-resource-calendar/components/arc-academic-semester-card.tsx	Switches semester date display to date-fns formatting.

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[Copilot]

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 5 comments.

Comments suppressed due to low confidence (1)

src/features/abstract-resource-calendar/utils/get-modal-header.test.ts:25

• clickedDay is expected to be the day key (e.g. "2024-03-15") coming from calendar clicks, but the test now passes a localized formatted string. Since getModalHeader formats clickedDay internally, this makes the test environment-dependent and may fail parsing. Pass the raw day key into getModalHeader and assert against the formatted output separately.

    const clickedDay = format(new Date("2024-03-15"), "dd MMMM yyyy", {
      locale: pl,
    });

    it("should return resource name with date for resource without relations", () => {
      const result = getModalHeader(Resource.CalendarEvents, clickedDay);
      expect(result).toBe(`Wydarzenia kalendarzowe ${clickedDay}`);
    });

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[kguzek]

LGTM