Align tooltip inside chart to reduce chance of overflow.

[hawjo01]

No description provided.

[github-actions]

LCOV of commit bf20e58 during Analyze and Test on Pull Request #41

Summary coverage rate:
  lines......: 54.5% (246 of 451 lines)
  functions..: no data found
  branches...: no data found

Files changed coverage rate:
                                          |Lines       |Functions  |Branches    
  Filename                                |Rate     Num|Rate    Num|Rate     Num
  ==============================================================================
  lib/widgets/records_line_chart.dart     | 0.0%     63|    -     0|    -      0