Release v1.0.0: Werkator

The release after 0.9.21 is 1.0.0, because a product that changes its
name is better off counting from one under it. The release note says as
much, so the jump is not read as a claim about maturity — plan steps 14,
17 and 18 are still open.

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 = "0.9.21"
+version = "1.0.0"
 
 java {
     toolchain {