[Feature]: Add month & year view modes to <Calendar> component

[kev-7777]

Describe the feature

The current Calendar component supports only day-level selection.
To build common UI patterns (MonthPicker, YearPicker, DateRange presets), we need additional view modes.

View modes:
view: 'day' | 'month' | 'year'

Events:
@month-select(month: number)
@year-select(year: number)

Example: https://primevue.org/datepicker/#monthpicker

Proposed minimal implementation:

• Add internal month grid (12 items)
• Add internal year grid (e.g. 12–20 years)

Thanks for considering this enhancement!

Additional information

• I intend to submit a PR for this feature.
• I have already implemented and/or tested this feature.

[caiotarifa]

Duplicated #1933