chore: update biome configurations and applied settings

[zimeg]

Summary

Forwards #2931 (biome v2 migration from main) into v5.

• Upgrades @biomejs/biome from v1 to v2
• Migrates biome config to v2 schema (ignore → includes, organizeImports → assist.actions.source)
• Applies biome v2 import/export ordering and lint fixes
• Adds override to relax unused variable checks in examples/
• Resolves merge conflicts with v5 changes (WorkflowStep removal, axios→fetch, error handling improvements)

No functional changes.

Test plan

• npm test passes (build + lint + types + coverage)

Co-Authored-By: Claude svc-devxp-claude@slack-corp.com

🤖 Generated with Claude Code

[changeset-bot]

⚠️ No Changeset found

Latest commit: 806bff7

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (v5@f63cfad). Learn more about missing BASE report.

Additional details and impacted files

@@          Coverage Diff          @@
##             v5    #2932   +/-   ##
=====================================
  Coverage      ?   94.11%           
=====================================
  Files         ?       42           
  Lines         ?     7295           
  Branches      ?      667           
=====================================
  Hits          ?     6866           
  Misses        ?      423           
  Partials      ?        6           

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[zimeg]

🔬 note: The "bolt-ts-custom-function-tempalte" is failing tests since earlier PR #2930 unrelated to this change. I'm eager to merge to keep the v5 branch near "main" changes!

Error: node_modules/@slack/web-api/dist/errors.d.ts(23,44): error TS2304: Cannot find name 'ErrorOptions'.