build(eslint-config-fluid): remove ESLint 8/9 compatibility layer

[tylerbutler]

Summary

Removes the ESLint 8/9 hybrid compatibility layer from eslint-config-fluid's print-configs script now that the migration to ESLint 9 flat config is complete.

• Delete .eslint-print-configs/ directory containing wrapper config files that were needed to bridge multi-export flat configs with ESLint's single-config-per-file requirement
• Remove cross-env dependency (no longer needed for ESLINT_USE_FLAT_CONFIG environment variable)
• Simplify print-configs.ts to import flat configs directly from flat.mjs and pass them via overrideConfig instead of using file paths
• Remove all conditional logic for legacy vs flat config formats

[Copilot]

Pull request overview

This pull request successfully removes the ESLint 8/9 hybrid compatibility layer from eslint-config-fluid, completing the migration to ESLint 9's flat config format. The changes eliminate temporary bridging infrastructure that was needed during the transition period.

Changes:

• Simplified print-configs.ts to import flat configs directly from flat.mjs and pass them via overrideConfig instead of using wrapper config files
• Removed cross-env dependency and ESLINT_USE_FLAT_CONFIG environment variable that were needed for dual ESLint 8/9 support
• Deleted .eslint-print-configs/ directory containing wrapper config files that bridged multi-export flat configs with ESLint's single-config-per-file requirement

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
common/build/eslint-config-fluid/scripts/print-configs.ts	Refactored to directly import and use flat config arrays instead of loading config files via paths; removed all conditional ESLint 8/9 compatibility logic
common/build/eslint-config-fluid/package.json	Removed cross-env dependency and simplified print-configs script to remove ESLINT_USE_FLAT_CONFIG environment variable
common/build/eslint-config-fluid/pnpm-lock.yaml	Removed cross-env and its dependency @epic-web/invariant from lock file; added libc annotations to resolver bindings (unrelated maintenance)
common/build/eslint-config-fluid/.eslint-print-configs/strict.mjs	Deleted wrapper config file (no longer needed with direct imports)
common/build/eslint-config-fluid/.eslint-print-configs/recommended.mjs	Deleted wrapper config file (no longer needed with direct imports)
common/build/eslint-config-fluid/.eslint-print-configs/minimal.mjs	Deleted wrapper config file (no longer needed with direct imports)
common/build/eslint-config-fluid/.eslint-print-configs/README.md	Deleted documentation for wrapper configs (no longer applicable)

Files not reviewed (1)

• common/build/eslint-config-fluid/pnpm-lock.yaml: Language not supported

[jason-ha]

No root pnpm-lock.yaml update? (I thought we had a temp funky config where root was also impacted by changes here.)

[jason-ha]

I expected the removal to just show removals.
What are the libc additions?

[tylerbutler]

I don't know - maybe because I ran install on macOS? Regardless, I manually cleaned up the lockfile changes to remove other unrelated changes and they're still considered up-to-date now so further evidence those other changes were unnecessary. But a fresh re-resolve still brings them back. 😕

[github-actions]

🔗 No broken links found! ✅

Your attention to detail is admirable.

linkcheck output

> fluid-framework-docs-site@0.0.0 ci:check-links /home/runner/work/FluidFramework/FluidFramework/docs
> start-server-and-test "npm run serve -- --no-open" 3000 check-links

1: starting server using command "npm run serve -- --no-open"
and when url "[ 'http://127.0.0.1:3000' ]" is responding with HTTP status code 200
running tests using command "npm run check-links"


> fluid-framework-docs-site@0.0.0 serve
> docusaurus serve --no-open

[SUCCESS] Serving "build" directory at: http://localhost:3000/

> fluid-framework-docs-site@0.0.0 check-links
> linkcheck http://localhost:3000 --skip-file skipped-urls.txt

Crawling...

Stats:
  252163 links
    1804 destination URLs
    2045 URLs ignored
       0 warnings
       0 errors