fix: bump version to 18.0.1 for 18.0 release

Why this change was needed:
Multiple SMELT-related features have been developed and merged onto the
18.0.x branch (smelt connector, smelt commands, assign priority/deadline
display, smelt_url config). The release is ready to be cut with these
features included.

Problem solved:
Users and downstream packagers get a single version number that reflects
all the features shipped in the 18.0 release, making it clear that
SMELT support is part of the release.

What changed:
- Bumped __version__ from 17.3.0 to 18.0.1
- Marked CHANGELOG.md [Unreleased] as [18.0.1] with today's date
- Bumped devel version to 18.1.0

Author: mimi1vx

CHANGELOG.md

@@ -5,7 +5,7 @@ All notable user-visible changes to MTUI are documented in this file.
 The format is based on [Keep a Changelog 1.1.0](https://keepachangelog.com/en/1.1.0/),
 and this project follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [18.0.1] - 2026-06-18
 
 ### Added
 

mtui/__init__.py

@@ -4,4 +4,4 @@
 multiple hosts in parallel, with a focus on maintenance update testing.
 """
 
-__version__ = "17.3.0"
+__version__ = "18.1.0"