robust json parsing & entity extraction progress log

[rangehow]

1. The JSON generated by large models may have issues such as being incomplete, redundant, or having formatting errors. The original solution was too brief and provided few prompts, so we made some improvements to address these.
2. Entity extraction is the most time-consuming part of this project, but there was no explicit progress indicator. We added a percentage indicator to let users know the current progress more clearly.

[codecov]

Codecov Report

Attention: Patch coverage is 90.74074% with 5 lines in your changes missing coverage. Please review.

Project coverage is 94.25%. Comparing base (1a85851) to head (ba3b2be).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
nano_graphrag/_utils.py	90.56%	5 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #55   +/-   ##
=======================================
  Coverage   94.25%   94.25%           
=======================================
  Files          12       12           
  Lines        1288     1288           
=======================================
  Hits         1214     1214           
  Misses         74       74           

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