fix: limit tool progress card to 16 lines max

[lishuceo]

Summary

• 工具调用进度卡片默认最多显示 16 行（之前是 40 行），超出部分省略，减少卡片过长干扰阅读

Test plan

• 52 个 message-builder 测试全部通过
• 截断逻辑不受影响（测试显式传 maxDisplayed=3）

🤖 Generated with Claude Code

[claude]

Claude finished @lishuceo's task in 28s —— View job

---

Review: PR #147

• Check previous review comments — no previous comments
• Read changed file and understand context
• Post review summary

---

✅ Approved — Clean, minimal change.

The PR changes the default maxDisplayed parameter from 40 to 16 in buildToolProgressCard(). The truncation logic (slice(-maxDisplayed) + omission notice) remains unchanged and correctly handles the new limit. Existing tests that explicitly pass maxDisplayed=3 are unaffected.

No bugs, no security issues, no architectural concerns.