Fix issue: Option to update username shown in conversations. (#975)

Co-authored-by: opencode-agent[bot] <opencode-agent[bot]@users.noreply.github.com>
Co-authored-by: thdxr <thdxr@users.noreply.github.com>

packages/opencode/src/app/app.ts

@@ -69,8 +69,12 @@ export namespace App {
 
     const root = git ?? input.cwd
 
+    // Load config to get custom username if set
+    const { Config } = await import("../config/config")
+    const config = await Config.global()
+    
     const info: Info = {
-      user: os.userInfo().username,
+      user: config.username || os.userInfo().username,
       hostname: os.hostname(),
       time: {
         initialized: state.initialized,