feat: terminal as a chosen OS user, create users from the panel (0.0.2)

- agent reports the OS user it runs as (enroll + poll header)
- per-machine terminal user on the edit page; defaults to the agent's own user (root on Linux)
- create a new user from the panel: name, password, optional sudo group
- show the reason in the terminal when a shell fails to start
- bump version to 0.0.2

internal/agent/task.go

@@ -54,9 +54,10 @@ func (a *Agent) postResult(ctx context.Context, taskID string, res proto.TaskRes
 	resp.Body.Close()
 }
 
-// execTask runs a single file-manager operation natively and returns a result.
+// execTask runs a single file-manager or user-management operation natively
+// and returns a result.
 func (a *Agent) execTask(env proto.TaskEnvelope) proto.TaskResult {
-	data, err := dispatchFS(env)
+	data, err := dispatchTask(env)
 	if err != nil {
 		return proto.TaskResult{Error: err.Error()}
 	}