fix: Enforce range endpoints, the ISO calendar rule, and int-only counts

[FBruzzesi]

Description

• range(..., step=2, inclusive="right") now returns the end it names instead of silently dropping both endpoints,
• the pandas/polars format checks reject weeks their year does not have (2023-W53), so a passing check is finally a valid precondition for the conversion that already rejected it.
• bool no longer counts as an integer in arithmetic, weeksout/daysout/range(step=)
• from_compact validates against the compact pattern it already carried;
• pandas builds ISO strings from isocalendar() rather than platform-dependent strftime("%G").
• Year-bound overflow is left reporting the standard library's own error, now documented and pinned by tests rather than wrapped.