perf: optimize advance() with lazy line/column tracking

[bartveneman]

• Replace per-character column tracking with lazy computation via getter
• Inline newline check using char_types bitmask to avoid function call
• Add seek() method for encapsulated lexer repositioning
• Update all sub-parsers to use seek() instead of direct property writes

Column is now computed as pos - _line_offset + 1 only when accessed, eliminating column++ on ~99% of characters (non-newlines).

[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 6 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@projectwallace/css-parser-esm	146.71kB	6 bytes (0.0%) ⬆️

Affected Assets, Files, and Routes:

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

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
parse-*.js	-92 bytes	25.97kB	-0.35%
parse-*.js	-92 bytes	22.88kB	-0.4%
parse-*.js	-22 bytes	8.48kB	-0.26%
parse-*.js	-36 bytes	7.15kB	-0.5%
parse-*.js	-46 bytes	8.47kB	-0.54%
tokenize.js	394 bytes	18.9kB	2.13%
char-*.js	-100 bytes	1.46kB	-6.43%

Files in parse-*.js:

• ./src/parse-selector.ts → Total Size: 24.59kB

Files in parse-*.js:

• ./src/parse-atrule-prelude.ts → Total Size: 22.08kB

Files in parse-*.js:

• ./src/parse-anplusb.ts → Total Size: 8.11kB

Files in parse-*.js:

• ./src/parse-declaration.ts → Total Size: 6.5kB

Files in parse-*.js:

• ./src/parse-value.ts → Total Size: 7.84kB

Files in tokenize.js:

• ./src/tokenize.ts → Total Size: 18.3kB

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.59259% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.87%. Comparing base (0fc9a60) to head (de388a6).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/tokenize.ts	90.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #148      +/-   ##
==========================================
- Coverage   94.96%   94.87%   -0.09%     
==========================================
  Files          16       16              
  Lines        2721     2714       -7     
  Branches      712      712              
==========================================
- Hits         2584     2575       -9     
- Misses        137      139       +2     

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