release automation: gitea actions build every push and publish tagged releases (version from the tag, packages, sha256sums, changelog section as text), simple 5-step install guide in the readme

build.gradle

@@ -4,7 +4,8 @@ plugins {
 }
 
 group = 'com.eliasmueller.llamamod'
-version = '0.2.0'
+// Release builds pass -PreleaseVersion=<tag without v> (see .gitea/workflows/release.yml).
+version = findProperty('releaseVersion') ?: '0.2.1'
 
 repositories {
     mavenCentral()