Add support for formatting CSS namespace selectors

[bartveneman]

Summary

This PR adds support for properly formatting CSS namespace selectors, including type selectors and universal selectors with namespace prefixes.

Key Changes

• Updated print_simple_selector() function to handle namespace prefixes for both type selectors (e.g., ns|div) and universal selectors (e.g., ns|*)
• Namespace prefixes are normalized to lowercase to match CSS specification conventions
• Added import for is_universal_selector utility function
• Added comprehensive test coverage for namespace selector formatting, including:
  • Named namespace prefixes (ns|div, ns|*)
  • Universal namespace prefix (*|div, *|*)
  • Empty namespace prefix (|div, |*)
  • Multiple selectors with namespaces (ns|div, ns|span)

Implementation Details

• Namespace prefixes are extracted from the node's namespace property and converted to lowercase before being prepended to the selector name
• The implementation handles both type selectors and universal selectors consistently
• Selectors without namespaces (where namespace is null) are formatted as before

https://claude.ai/code/session_01HfazKmPqWt1wtBF3ZUJ53P

[codecov]

Bundle Report

Changes will increase total bundle size by 209 bytes (1.22%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
formatCss-esm	14.61kB	209 bytes (1.45%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: formatCss-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
index.js	209 bytes	13.08kB	1.62%

Files in index.js:

• ./src/lib/index.ts → Total Size: 12.6kB

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.83%. Comparing base (53000db) to head (5275926).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #209      +/-   ##
==========================================
+ Coverage   96.80%   96.83%   +0.03%     
==========================================
  Files           2        2              
  Lines         344      348       +4     
  Branches      124      127       +3     
==========================================
+ Hits          333      337       +4     
  Misses         10       10              
  Partials        1        1              

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