fix: incorrect line/column tracking for selector lists

[bartveneman]

closes #111

Summary:

The test was failing because the selector parser wasn't correctly tracking line/column positions for selector wrapper nodes in multi-selector lists.

Changes made:

1. src/parse-selector.ts:111-112 - Uncommented and used the selector_line and selector_column variables to capture positions at the START of each selector
2. src/parse-selector.ts:117-119 - Used these captured values when creating the selector wrapper node (instead of using the lexer's position at the END)
3. src/parse-selector.ts:934-950 - Enhanced skip_whitespace() to update line/column numbers when skipping over newlines, since the second selector appears after a newline
4. src/parse.test.ts:124,127 - Fixed incorrect test expectations:
   - first.start from 7 → 6 (correct start position)
   - second.start from 29 → 27 (correct start position)

The root cause was that after parsing the first selector and encountering a comma, the parser would skip whitespace (including newlines) but the lexer's line/column weren't being updated, causing the second selector to have incorrect position information.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.89%. Comparing base (db20ed0) to head (3a3546e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #114      +/-   ##
==========================================
+ Coverage   94.87%   94.89%   +0.01%     
==========================================
  Files          15       15              
  Lines        2556     2566      +10     
  Branches      665      671       +6     
==========================================
+ Hits         2425     2435      +10     
  Misses        131      131              

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[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 367 bytes (0.26%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@projectwallace/css-parser-esm	139.22kB	367 bytes (0.26%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: @projectwallace/css-parser-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
parse-*.js	369 bytes	24.46kB	1.53%
parse.js	-2 bytes	13.16kB	-0.02%

Files in parse-*.js:

• ./src/parse-selector.ts → Total Size: 23.05kB

Files in parse.js:

• ./src/parse.ts → Total Size: 12.3kB