fix: remove trailing newline after last rendered line

[Harsh-Anand-Singh]

Description

Removes a stray trailing \n that CodeView was emitting after the last rendered line in both the plain-text and syntax-highlighted render paths. Output now equals input verbatim, and user-supplied trailing newlines are preserved.

Related links, issue #, if available: n/a

How has this been tested?

• Added unit tests asserting exact textContent for single-line, multi-line, trailing-newline, and highlighted inputs.
• All existing unit tests pass.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.29%. Comparing base (d6a888c) to head (fbbb507).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #139      +/-   ##
==========================================
- Coverage   99.64%   99.29%   -0.36%     
==========================================
  Files          29       29              
  Lines         284      284              
  Branches       33       35       +2     
==========================================
- Hits          283      282       -1     
  Misses          1        1              
- Partials        0        1       +1     

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