feat: configure Maven Central publishing with Vanniktech plugin

Set up complete publishing infrastructure for Maven Central Portal:
- Added Vanniktech Maven Publish plugin (0.30.0) for new Portal API
- Updated Dokka to 2.1.0 with V2 migration enabled
- Updated Ktor dependencies to 3.3.1
- Configured POM metadata (MIT license, developer info, SCM)
- Set JVM toolchain to 17 for wide compatibility
- Disabled configuration cache (incompatible with publishing)
- Configured GPG signing with signAllPublications()

Also created comprehensive journal documenting the entire setup process,
including GPG key configuration, secring.gpg generation, and detailed
pre-release checklist for final publication.

Phase 2 (Maven Central setup) in progress - artifacts uploaded to Portal,
awaiting final pre-release checks before publishing v0.1.0.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: Jonas Saabel

build.gradle.kts

@@ -3,9 +3,11 @@ import com.github.benmanes.gradle.versions.updates.DependencyUpdatesTask
 plugins {
     application
     alias(libs.plugins.ben.manes.versions)
+    alias(libs.plugins.dokka)
     alias(libs.plugins.kotlin.jvm)
     alias(libs.plugins.kotlin.serialization)
     alias(libs.plugins.kotlinter)
+    alias(libs.plugins.maven.publish)
 }
 
 group = "it.saabel"
@@ -54,3 +56,51 @@ tasks.withType<DependencyUpdatesTask> {
         isNonStable(candidate.version) && !isNonStable(currentVersion)
     }
 }
+
+// Configure Java plugin for JVM toolchain
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(17))
+    }
+}
+
+// Vanniktech Maven Publish Plugin Configuration
+mavenPublishing {
+    // Publish to Maven Central Portal (new system)
+    publishToMavenCentral(com.vanniktech.maven.publish.SonatypeHost.CENTRAL_PORTAL)
+
+    // Sign all publications with GPG
+    signAllPublications()
+
+    // Configure POM metadata
+    coordinates("it.saabel", "kotlin-notion-client", "0.1.0")
+
+    pom {
+        name.set("Kotlin Notion Client")
+        description.set("A modern, type-safe Kotlin client for the Notion API with comprehensive DSL support and coroutine-based operations")
+        url.set("https://github.com/jsaabel/kotlin-notion-client")
+
+        licenses {
+            license {
+                name.set("MIT License")
+                url.set("https://opensource.org/licenses/MIT")
+                distribution.set("repo")
+            }
+        }
+
+        developers {
+            developer {
+                id.set("jsaabel")
+                name.set("Jonas Saabel")
+                email.set("jonas@saabel.it")
+                url.set("https://saabel.it")
+            }
+        }
+
+        scm {
+            connection.set("scm:git:git://github.com/jsaabel/kotlin-notion-client.git")
+            developerConnection.set("scm:git:ssh://github.com/jsaabel/kotlin-notion-client.git")
+            url.set("https://github.com/jsaabel/kotlin-notion-client")
+        }
+    }
+}

gradle.properties

@@ -1,2 +1,3 @@
 kotlin.code.style=official
-org.gradle.configuration-cache=true
+org.gradle.configuration-cache=false
+org.jetbrains.dokka.experimental.gradle.pluginMode=V2EnabledWithHelpers

gradle/libs.versions.toml

@@ -1,23 +1,27 @@
 [versions]
-kotest = "6.0.3"
+kotest = "6.0.4"
 ben-manes-versions = "0.53.0"
+dokka = "2.1.0"
 kotlin = "2.2.20"
 kotlinter = "5.2.0"
+maven-publish = "0.30.0"
 # kotlinx-datetime: Using 0.6.2 instead of 0.7.x because 0.7.x migrated to kotlin.time.Instant
 # which is still @ExperimentalTime in Kotlin 2.2. Using experimental APIs in a library is
 # problematic as it forces instability on users. 0.6.x uses stable kotlinx.datetime.Instant.
 # We'll upgrade to 0.7.x+ when kotlin.time types are stabilized (likely Kotlin 2.3+).
 kotlinx-datetime = "0.6.2"
 kotlinx-serialization-json = "1.9.0"
-ktor = "3.3.0"
+ktor = "3.3.1"
 logback = "1.5.19"
 slf4j = "2.0.17"
 
 [plugins]
 ben-manes-versions = { id = "com.github.ben-manes.versions", version.ref = "ben-manes-versions" }
+dokka = { id = "org.jetbrains.dokka", version.ref = "dokka" }
 kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }
 kotlin-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlin" }
 kotlinter = { id = "org.jmailen.kotlinter", version.ref = "kotlinter" }
+maven-publish = { id = "com.vanniktech.maven.publish", version.ref = "maven-publish" }
 
 [libraries]
 kotest-runner-junit5 = { group = "io.kotest", name = "kotest-runner-junit5", version.ref = "kotest" }