Chatify 0.2.5

Fix the version shown by chatify --version, which still read 0.2.3 in the 0.2.4 build, and add a test so the package version, project metadata and installer release can never drift apart again.

Everything in 0.2.4 applies: context-swapping composer actions, state-announcing controls, exposed keyboard shortcuts, code blocks with per-block copy, and repaired strict UI tests.