docs(changelog): release v0.25.0

Rolls [Unreleased] into [0.25.0] - 2026-10-05 and leaves a fresh empty
[Unreleased] on top. The section already carried an entry for every
user-facing change since v0.24.0, including the Mendix 11.15 message
definition and mapping fixes merged just before the release; this adds
the mandatory headline and puts the sections in the canonical
Added / Changed / Fixed order.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HcTT1J4176oUMZ87AY9aBk

Author: ako