feat(qq): stream the full turn feed as discrete messages

Show what the agent is actually doing during a turn, the way Claude
Code does: interim explanation text, every Tool call, and the error
detail when a tool fails, each as its own pushed message before the
final markdown answer.

- HarnessReplyTracker.consume now returns every frame of a polling
  batch in order (same-batch text frames collapse to the latest)
  instead of dropping all but the last event, which silently ate
  tool-call frames that shared a batch with their result
- tool frames carry callId; status frames carry the correlated
  toolName and a flattened error text parsed from the tool/result
  error payload (message, or name: code)
- the QQ bridge holds interim step text until the next tool call
  (or the end of the turn) pushes it, emits 'Tool call <name>' per
  call, emits 'Tool call <name>\nError: <reason>' for failures, and
  skips re-sending interim text that already equals the final answer

Other channels keep their existing behaviour: the status frame still
reads '正在整理结果…' and they ignore the new optional fields.

test/channels/dingtalk/harness-client.test.mjs

@@ -399,7 +399,7 @@ test('reply tracker associates only the Harness turn created by the DingTalk pro
       data: { turn: 9, step: 0, chunk: { type: 'text-delta', index: 0, text: '钉钉' } },
     } },
   ]);
-  assert.deepEqual(update, { type: 'text', text: '钉钉' });
+  assert.deepEqual(update, [{ type: 'text', text: '钉钉' }]);
   tracker.consume([
     { event: {
       seq: 6,