feat(transformers): add transformerMetaDiff

[Divyapahuja31]

• -

Description

This PR introduces transformerMetaDiff to support diff highlighting via meta string.

Syntax:

• {1+} marks line 1 as added (diff add).
• {3-5-} marks lines 3-5 as removed (diff remove).

Example:

console.log('added')
console.log('kept')
console.log('removed')

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[codecov]

Codecov Report

❌ Patch coverage is 96.72131% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.26%. Comparing base (49cbb76) to head (42c52fb).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ackages/transformers/src/transformers/meta-diff.ts	96.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1240      +/-   ##
==========================================
+ Coverage   95.25%   95.26%   +0.01%     
==========================================
  Files          92       93       +1     
  Lines        8007     8069      +62     
  Branches     1705     1723      +18     
==========================================
+ Hits         7627     7687      +60     
- Misses        374      376       +2     
  Partials        6        6              

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