Fix pgn disambiguation squares

[CorentinGS]

WIP for #73

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.42%. Comparing base (34f57bc) to head (fb28e4b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #75      +/-   ##
==========================================
+ Coverage   68.51%   69.42%   +0.90%     
==========================================
  Files          27       27              
  Lines        4872     4889      +17     
==========================================
+ Hits         3338     3394      +56     
+ Misses       1410     1371      -39     
  Partials      124      124              

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[Copilot]

Pull Request Overview

This pull request fixes PGN disambiguation parsing by adding support for full square disambiguation in chess moves like "Qe8f7" (queen from e8 to f7). Currently, such moves fail to parse because the parser doesn't handle complete square disambiguation properly.

Key changes:

• Adds a new DeambiguationSquare token type for lexical analysis
• Implements parsing logic for full square disambiguation in moves
• Includes comprehensive test coverage for various disambiguation scenarios

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
pgn_disambiguation_test.go	Adds test cases for PGN disambiguation parsing and tokenizer functionality
pgn.go	Updates move parser to handle DeambiguationSquare tokens with origin file and rank extraction
lexer.go	Adds DeambiguationSquare token type and lexing logic for full square disambiguation

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[Copilot]

The comment indicates uncertainty about the expected token sequence. Either remove this comment if the expectation is correct, or fix the expected tokens if they are indeed wrong as the comment suggests.

Suggested change

	expected: []TokenType{PIECE, DeambiguationSquare, SQUARE}, // This is likely wrong - should be PIECE, SQUARE (source), SQUARE (dest)
	expected: []TokenType{PIECE, SQUARE, SQUARE},