refactor: extract maven-publish configuration to publish-convention plugin

- Created `publish-convention.gradle.kts` for centralizing publishing setup.
- Replaced direct `maven-publish` usage with `publish-convention` plugin in build scripts.
- Simplified `core-convention` by delegating publishing configuration to the new plugin.

Author: twisti-dev

buildSrc/src/main/kotlin/core-convention.gradle.kts

@@ -6,7 +6,7 @@ val libs = the<LibrariesForLibs>()
 plugins {
     java
     `java-library`
-    `maven-publish`
+    id("publish-convention")
 
     kotlin("jvm")
     kotlin("plugin.serialization")
@@ -54,21 +54,6 @@ java {
     }
 }
 
-publishing {
-    repositories {
-        maven("https://repo.slne.dev/repository/maven-releases/") {
-            name = "maven-releases"
-            credentials {
-                username = System.getenv("SLNE_RELEASES_REPO_USERNAME")
-                password = System.getenv("SLNE_RELEASES_REPO_PASSWORD")
-            }
-        }
-    }
-
-    publications.create<MavenPublication>("maven") {
-        from(components["java"])
-    }
-}
 
 configurations {
     compileOnly {

buildSrc/src/main/kotlin/publish-convention.gradle.kts

@@ -0,0 +1,19 @@
+plugins {
+    `maven-publish`
+}
+
+publishing {
+    repositories {
+        maven("https://repo.slne.dev/repository/maven-releases/") {
+            name = "maven-releases"
+            credentials {
+                username = System.getenv("SLNE_RELEASES_REPO_USERNAME")
+                password = System.getenv("SLNE_RELEASES_REPO_PASSWORD")
+            }
+        }
+    }
+
+    publications.create<MavenPublication>("maven") {
+        from(components["java"])
+    }
+}

surf-api-gradle-plugin/surf-api-processor/build.gradle.kts

@@ -6,6 +6,7 @@ val snapshot = (findProperty("snapshot") as String).toBooleanStrict()
 
 plugins {
     kotlin("jvm")
+    `publish-convention`
 }
 
 group = groupId