chore: LSTM 训练调优总结 — 类别加权/采样器/权重多项尝试，XGBoost 仍为最佳

src/data/download_era5.py

@@ -39,18 +39,25 @@ def download_one_month(city: str, year: int, month: int) -> bool:
         return True  # 已存在，跳过
 
     request = build_request(city, year, month)
-    for attempt in range(1, 4):
+    for attempt in range(1, 6):
         try:
+            logger.info("请求 %s %d-%02d (第 %d/5 次)", city, year, month, attempt)
             client.retrieve("reanalysis-era5-land", request, str(out_path))
-            return True
-        except Exception:
-            if attempt < 3:
-                time.sleep(30)
+            if out_path.exists() and out_path.stat().st_size > 0:
+                return True
+            else:
+                logger.warning("文件为空 %s %d-%02d，重试", city, year, month)
+        except Exception as e:
+            delay = 60 * attempt
+            logger.warning("失败 %s %d-%02d (第 %d/5 次): %s，%ds 后重试",
+                           city, year, month, attempt, str(e)[:100], delay)
+            if attempt < 5:
+                time.sleep(delay)
     return False
 
 
 def download_city(city: str, start_year: int = ERA5_START_YEAR,
-                   end_year: int = ERA5_END_YEAR, max_workers: int = 3):
+                   end_year: int = ERA5_END_YEAR, max_workers: int = 1):
     """并行下载（3线程），兼顾速度和 CDS 限流"""
     name = CITIES[city]["name"]
     tasks = [(city, y, m) for y in range(start_year, end_year + 1) for m in range(1, 13)]