refactor: redesign plugin system and enhance message handling

- Move plugin and tool-related classes to a dedicated `Plugin-API` module.
- Introduce a new plugin lifecycle (`onInit`, `onEnable`, `onDisable`) and a more robust `Tool` API.
- Refactor `Core` to use `PrintAdvanceMessageHandler` for improved handling of assistant messages, tool responses, and errors.
- Rename `PluginLoader` to `Loader` and migrate it to `me.zacharias.chat.plugin.loader`.
- Update build configurations and Java toolchains across modules.
- Clean up obsolete plugin annotations and interfaces in the `Core` module.

build.gradle

@@ -21,7 +21,6 @@ subprojects {
     apply plugin: 'com.gradleup.shadow'
 
     dependencies {
-        implementation("org.json:json:20250107")
         implementation("org.jetbrains:annotations:23.1.0")
 
         testImplementation 'org.junit.jupiter:junit-jupiter:5.10.0'
@@ -73,4 +72,22 @@ subprojects {
             }
         }
     }
+
+    publishing {
+        publications {
+            maven(MavenPublication) {
+                from components.java
+            }
+        }
+        repositories {
+            maven {
+                name = "gitea"
+                url = "https://git.server.4zellen.se/api/packages/Chat_things/maven"
+                credentials {
+                    username = project.findProperty("giteaUser")
+                    password = project.findProperty("giteaToken")
+                }
+            }
+        }
+    }
 }