Give development builds their own Debian package version

make deb versions a build that isn't a release after the last tag:
0.2.0~rc.1+git3.gca0f148, plus the build time (.m<UTC time>) with
uncommitted changes. apt sorts it after that RC and before the next, so
installing it over the RC or an older build is an upgrade and needs no
--reinstall. mkdeb.sh removes older packages of the same architecture
from dist/ so the install globs match one package.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/mkdeb.sh

@@ -54,6 +54,9 @@ fi
 work=dist/deb/${DEB_VERSION}_${DEB_ARCH}
 stage=$work/stage
 rm -rf "$work"
+# Older packages of this architecture (every development build has its
+# own version), so 'apt install ./dist/jarl_*_amd64.deb' finds just one.
+rm -f dist/jarl_*_"$DEB_ARCH".deb dist/jarl-cli_*_"$DEB_ARCH".deb
 mkdir -p "$stage"
 
 # Binaries for the package's architecture (bin/ holds the host's, which