Release v0.9.21: the watcher's reach into origin is visible

Also fixes the log-capture test added with step 19: the test JVM logs at
WARN, so the INFO line reporting the recovered fetch never reached the
appender. The helper now lowers the level explicitly.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

build.gradle.kts

@@ -12,7 +12,7 @@ group = "de.hoennig"
 // bump at least the patch version for every deployment — and only then, not per commit —
 // so the UI footer (BuildProperties), --version and the release notes identify what is
 // actually running; a deployment bundles whatever was committed since the last one
-version = "0.9.20"
+version = "0.9.21"
 
 java {
     toolchain {