Refactor walk and traverse to use arena-based node access

[bartveneman]

Summary

Refactored the walk() and traverse() functions to directly access the CSS data arena instead of relying on node object properties. This change improves performance by avoiding repeated object property lookups and enables more efficient tree traversal.

Key Changes

• Refactored walk() function: Now extracts arena, source, and index from the node and uses arena methods (get_type(), get_first_child(), get_next_sibling()) for traversal instead of accessing node properties
• Refactored traverse() function: Similarly updated to use arena-based access for both enter and leave callbacks
• Introduced internal helper functions: Added _walk() and _traverse() private functions that accept arena, source, and index parameters to avoid repeated extraction logic
• Added internal accessors to CSSNode: Exposed __get_source() and __get_index() methods to allow walk/traverse functions to access the underlying data needed for arena operations
• Updated .gitignore: Added package-lock.json to ignore list

Implementation Details

• The refactoring maintains the same public API and control flow behavior (BREAK, SKIP)
• Child traversal now uses arena indices (with 0 as null sentinel) instead of null-based linked list navigation
• Depth calculation logic remains unchanged but is now applied consistently in both public and private functions
• The helper functions reduce code duplication between the public entry points and recursive traversal logic

https://claude.ai/code/session_01UVBKCBKB11qjh9k2PwbLen

[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 1.48kB (0.78%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@projectwallace/css-parser-esm	190.88kB	1.48kB (0.78%) ⬆️

Affected Assets, Files, and Routes:

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

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
css-node-BTgoFWDU.js (New)	14.88kB	14.88kB	100.0% 🚀
walk.js	1.36kB	3.18kB	74.56% ⚠️
css-node-C3t4b8Jt.js (Deleted)	-14.76kB	0 bytes	-100.0% 🗑️

Files in css-node-BTgoFWDU.js:

• ./src/css-node.ts → Total Size: 14.66kB

Files in walk.js:

• ./src/walk.ts → Total Size: 3.03kB

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.20%. Comparing base (2f19177) to head (2437dc7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #247      +/-   ##
==========================================
+ Coverage   93.14%   93.20%   +0.06%     
==========================================
  Files          17       17              
  Lines        3035     3062      +27     
  Branches      845      853       +8     
==========================================
+ Hits         2827     2854      +27     
  Misses        208      208              

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