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.

Core/src/test/java/plugin/Tool.java

@@ -6,6 +6,7 @@ import me.zacharias.chat.ollama.OllamaPerameter;
 import me.zacharias.chat.ollama.OllamaToolRespnce;
 import me.zacharias.chat.plugin.annotation.OllamaTool;
 import me.zacharias.chat.plugin.annotation.injectons.InjectPlugin;
+import org.jetbrains.annotations.NotNull;
 
 @OllamaTool
 public class Tool extends OllamaFunctionTool {
@@ -13,7 +14,7 @@ public class Tool extends OllamaFunctionTool {
     Test core;
 
     @Override
-    public String name() {
+    public @NotNull String name() {
         return "";
     }
 
@@ -23,7 +24,7 @@ public class Tool extends OllamaFunctionTool {
     }
 
     @Override
-    public OllamaPerameter parameters() {
+    public @NotNull OllamaPerameter parameters() {
         return null;
     }