fix(drift-card): 修 drift 卡片 2 bug — AI 研判 copy 樣式 + Diff 按鈕 AttributeError

Bug 1: 按「🔍 查看 Diff」失敗
  錯誤: 'DriftReportRepository' object has no attribute 'get_by_id'
  根因: DriftReportRepository 方法叫 get(), 其他 repo 都叫 get_by_id()
  修法: 加 get_by_id() alias, 對齊 repo 介面慣例

Bug 2: AI 研判內容被渲染成 code block + copy 按鈕
  根因: telegram_gateway line 1962 用 <pre> 包 diff_summary
       但 diff_summary 是 AI 研判敘述 + emoji 清單, 非 code
  修法: 移除 <pre>, 改以分隔線 + html.escape 純文字顯示

驗收:
- 下次 drift 卡片: AI 研判段落純文字(無紫色 code block + copy)
- 按「🔍 查看 Diff」→ 送完整 diff 詳情(非 AttributeError)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/api/src/repositories/drift_repository.py

@@ -116,6 +116,11 @@ class DriftReportRepository:
             row = result.fetchone()
         return _row_to_report(row) if row else None
 
+    # 2026-04-19 Claude Opus 4.7 修 drift_view 按鈕 AttributeError
+    # 其他 repo 慣例皆 get_by_id，對齊介面供 telegram_gateway 呼叫
+    async def get_by_id(self, report_id: str) -> DriftReport | None:
+        return await self.get(report_id)
+
     async def list_recent(self, limit: int = 50) -> list[DriftReport]:
         """列出最近 N 筆（倒序）"""
         async with get_db_context() as db: