Add six new stylelint rules for CSS metrics analysis

[bartveneman]

Summary

This PR adds six new stylelint rules to the plugin that leverage the @projectwallace/css-analyzer library to enforce CSS quality metrics and constraints.

Key Changes

• New Rules Added:

  • max-file-size: Enforces a maximum file size limit in bytes
  • max-embedded-content-size: Limits the total size of embedded content (data URIs, etc.)
  • max-comment-size: Restricts the total size of CSS comments
  • max-average-selectors-per-rule: Enforces a maximum average number of selectors per rule
  • max-average-declarations-per-rule: Enforces a maximum average number of declarations per rule
  • max-average-selector-complexity: Enforces a maximum average selector complexity

• Implementation Details:

  • Each rule follows the same pattern: validate options, analyze CSS using @projectwallace/css-analyzer, compare actual metrics against configured thresholds, and report violations
  • All rules skip execution when configured with values ≤ 0 (except max-important-ratio which uses < 0)
  • Comprehensive test coverage for each rule covering edge cases (disabled config, no violations, within limits, exceeding limits)
  • Rules are exported in the main plugin index and included in the recommended configuration

• Documentation Updates:

  • Updated README.md with example configurations for all new rules
  • Added rules to the recommended configuration with sensible defaults
  • Updated plugin exports and test suite to include new rules

Notable Implementation Details

• All rules use the same CSS analysis approach via analyze(root.source!.input.css)
• Error messages are contextual and include both actual and expected values
• Rules properly integrate with stylelint's validation and reporting utilities
• Test suite uses Vitest and validates both positive cases (no errors) and negative cases (errors reported)

https://claude.ai/code/session_01N4LARBRwbeExNaaiACWJT6

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.99%. Comparing base (25affd6) to head (37e2ce7).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #58      +/-   ##
==========================================
+ Coverage   97.46%   97.99%   +0.53%     
==========================================
  Files          18       25       +7     
  Lines         591      749     +158     
  Branches      189      210      +21     
==========================================
+ Hits          576      734     +158     
  Misses         12       12              
  Partials        3        3              

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[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 10.95kB (28.17%) ⬆️⚠️, exceeding the configured threshold of 5%.

Bundle name	Size	Change
stylelintPlugin-esm	49.82kB	10.95kB (28.17%) ⬆️⚠️

Affected Assets, Files, and Routes:

view changes for bundle: stylelintPlugin-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
index.mjs	10.22kB	47.21kB	27.64% ⚠️
configs/recommended.d.mts	384 bytes	1.27kB	43.49% ⚠️
configs/recommended.mjs	343 bytes	1.2kB	40.26% ⚠️

Files in index.mjs:

• ./src/rules/max-embedded-content-size/index.ts → Total Size: 1.46kB

• ./src/rules/max-file-size/index.ts → Total Size: 1.11kB

• ./src/rules/max-average-selectors-per-rule/index.ts → Total Size: 1.41kB

• ./src/index.ts → Total Size: 763 bytes

• ./src/rules/max-important-ratio/index.ts → Total Size: 1.48kB

• ./src/rules/max-comment-size/index.ts → Total Size: 1.32kB

• ./src/rules/max-average-selector-complexity/index.ts → Total Size: 1.5kB

• ./src/rules/max-average-declarations-per-rule/index.ts → Total Size: 1.45kB

Files in configs/recommended.mjs:

• ./src/configs/recommended.ts → Total Size: 1.15kB