fix: add namespace getter for type selectors

[bartveneman]

feat: add namespace property to TypeSelector and UniversalSelector

Fixes the selector namespace API:

• TypeSelector.name now always returns the local element name (e.g.
  'div' for both div and ns|div). Previously it returned the
  namespace prefix for namespaced selectors, making it impossible to
  get the element name without parsing .text manually.

• UniversalSelector.name now always returns null. Previously it
  returned '*' for both plain * and *|*, making the two
  indistinguishable.

• New namespace property on both types returns the namespace prefix:
  null (no qualifier), '' (empty, |div), 'ns' (named), or
  '*' (any-namespace wildcard).

Implementation: adds FLAG_HAS_NAMESPACE (bit 4 in the flags byte).
When set, content fields hold the local name and value fields hold the
namespace prefix. The flag distinguishes |div (empty namespace, flag
set, value length 0) from plain div (no qualifier, flag not set).

[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 1.13kB (0.61%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@projectwallace/css-parser-esm	185.51kB	1.13kB (0.61%) ⬆️

Affected Assets, Files, and Routes:

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

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
node-types-DJytj0FB.d.ts (New)	23.63kB	23.63kB	100.0% 🚀
parse-selector.js	254 bytes	19.2kB	1.34%
css-node-C3t4b8Jt.js (New)	14.76kB	14.76kB	100.0% 🚀
node-types-CORQtdPo.d.ts (Deleted)	-23.37kB	0 bytes	-100.0% 🗑️
css-node-2WA1GE9K.js (Deleted)	-14.14kB	0 bytes	-100.0% 🗑️

Files in parse-selector.js:

• ./src/parse-selector.ts → Total Size: 18.67kB

Files in css-node-C3t4b8Jt.js:

• ./src/css-node.ts → Total Size: 14.54kB

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.86%. Comparing base (95e119a) to head (dd2d55c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #228      +/-   ##
==========================================
+ Coverage   93.83%   93.86%   +0.02%     
==========================================
  Files          17       17              
  Lines        2951     2965      +14     
  Branches      805      808       +3     
==========================================
+ Hits         2769     2783      +14     
  Misses        182      182              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.