Attach the jars to GitHub releases instead of CI runs

.github/workflows/build.yml

@@ -19,8 +19,5 @@ jobs:
           java-version: "25"
       - uses: gradle/actions/setup-gradle@v6
       # Test sources stay local (not in the repository): this compiles everything and checks the shipped jars.
+      # The jars themselves are attached to GitHub releases (release.yml), not to PR or push runs.
       - run: ./gradlew build
-      - uses: actions/upload-artifact@v7
-        with:
-          name: friends-plugins
-          path: builds/*.jar

.github/workflows/release.yml

@@ -0,0 +1,29 @@
+name: release
+
+# Publishing a GitHub release builds its tag and attaches the jars from builds/ to that release.
+on:
+  release:
+    types: [published]
+
+permissions:
+  contents: write # upload release assets
+
+jobs:
+  jars:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: actions/setup-java@v6
+        with:
+          distribution: temurin
+          java-version: "25"
+      - uses: gradle/actions/setup-gradle@v6
+      # A v0.6.0 release must not get 0.5.0 jars: the tag has to match the project version.
+      - run: 'grep -q "version = \"${TAG#v}\"" build.gradle.kts || { echo "tag $TAG does not match the project version"; exit 1; }'
+        env:
+          TAG: ${{ github.event.release.tag_name }}
+      - run: ./gradlew build
+      - run: gh release upload "$TAG" builds/*.jar --clobber
+        env:
+          GH_TOKEN: ${{ github.token }}
+          TAG: ${{ github.event.release.tag_name }}

README.md

@@ -17,7 +17,8 @@ Modules (one folder per part; a new platform gets its own top-level folder next
 ./gradlew build   # tests, then builds/friends-paper.jar, friends-velocity.jar, friends-bungee.jar, friends-api.jar
 ```
 
-Put the jar for your platform in `plugins/`. Every server/proxy must run **Java 25** (Velocity 4.2 and Paper 26.x
+Or download the jars from the [GitHub releases](https://github.com/Macaron27/Friends/releases) (each release builds and
+attaches them). Put the jar for your platform in `plugins/`. Every server/proxy must run **Java 25** (Velocity 4.2 and Paper 26.x
 require it anyway; older Paper versions run on it, see below). Add `--enable-native-access=ALL-UNNAMED` to the JVM
 flags to silence the JDK warning about SQLite's native library.