feat: add initial implementation of Opencode client and session handling

- Created agent.ts to export necessary components from the plugin source.
- Implemented index.ts to initialize Opencode client and list projects and sessions.
- Added functionality to prompt a session with specific tool instructions.

plugin/src/index.ts

@@ -1,8 +1,8 @@
 import { tool } from "@opencode-ai/plugin/tool";
 import type { Plugin, PluginInput } from "@opencode-ai/plugin";
 
-const MyPlugin: Plugin = async (ctx: PluginInput) => {
-  console.log("Plugin loaded!", ctx.project.name);
+export const MyPlugin: Plugin = async (ctx: PluginInput) => {
+  console.log("Plugin loaded!", ctx.project.worktree);
 
   return {
     tool: {
@@ -19,4 +19,3 @@ const MyPlugin: Plugin = async (ctx: PluginInput) => {
   };
 };
 
-export default MyPlugin;