chore: preserve step-aware logging after upstream sync

- 吸收 master 的核心改动：按可见步骤归类日志显示，覆盖 OAuth、手机号验证、平台验证和内容脚本日志链路。

- 本地补充修复：保留平台验证成功后的手机号接码确认收尾，避免 #193/#194 恢复的手机号复用链路被合并覆盖。

- 影响范围：background routing、phone verification、platform verify、content scripts、sidepanel 与相关测试/文档。

sidepanel/sidepanel.js

@@ -8390,8 +8390,8 @@ function appendLog(entry) {
   const line = document.createElement('div');
   line.className = `log-line log-${entry.level}`;
 
-  const stepMatch = entry.message.match(/(?:Step\s+(\d+)|步骤\s*(\d+))/);
-  const stepNum = stepMatch ? (stepMatch[1] || stepMatch[2]) : null;
+  const normalizedStep = Math.floor(Number(entry.step) || 0);
+  const stepNum = normalizedStep > 0 ? String(normalizedStep) : null;
 
   let html = `<span class="log-time">${time}</span> `;
   html += `<span class="log-level log-level-${entry.level}">${levelLabel}</span> `;