fix(heatmap): 使用绝对路径并去掉热力图月份和星期标签

- 文件路径改为基于 __file__ 的绝对路径，确保 cron 运行时正确保存
- 去掉 weekday_label 和 month_label 避免文字挤在一起

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

heatmap.py

@@ -18,7 +18,8 @@ client = Mastodon(
     api_base_url="https://nofan.xyz",
 )
 
-fn = "./heatmap.txt"
+base_dir = os.path.dirname(os.path.abspath(__file__))
+fn = os.path.join(base_dir, "heatmap.txt")
 # read from file if exists
 date = []
 data = []
@@ -79,9 +80,9 @@ with open(fn, "w") as f:
     f.close()
 
 cleaned_date, cleaned_data = july.utils.preprocess_inputs(date, data)
-july.heatmap(cleaned_date, cleaned_data, cmap="BuGn")
+july.heatmap(cleaned_date, cleaned_data, cmap="BuGn", month_grid=False, weekday_label=False, month_label=False)
 
-img_path = "./heatmap.png"
+img_path = os.path.join(base_dir, "heatmap.png")
 plt.savefig(img_path, bbox_inches="tight")
 
 # upload image to mastodon