Upgrade Tailwind CSS from v3 to v4

[Copilot]

Migrates Tailwind CSS from v3.4.17 to v4.1.18, adopting v4's CSS-first architecture.

Changes

• CSS syntax: Replaced @tailwind directives with @import 'tailwindcss' in src/input.css
• CLI package: Added @tailwindcss/cli v4.1.18 as separate dependency (v4 splits CLI from core)
• Configuration: Removed tailwind.config.js (v4 auto-detects content, no custom theme defined)
• Generated output: CSS now uses v4's custom property-based theme system

Base Branch Merges

• Merged base branch renovate/major-tailwindcss-monorepo twice to resolve conflicts
• Updated dependencies from base branch:
  • @babel/runtime 7.26.10
  • @typescript-eslint 8.54.0
  • webpack 5.105.0
  • @biomejs/biome 2.3.14 (Biome v2 migration)
• Incorporated Biome v2 migration changes (updated lint script syntax)
• Incorporated tsconfig JSX transform updates
• Regenerated pnpm-lock.yaml and dist/css/popup.css with all updates

Testing

All 161 tests pass, confirming UI functionality is preserved. Build, TypeScript compilation, and linter all succeed with updated toolchain.

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[hogashi]

@copilot resolve conflict (either merge or rebase is ok)

[Copilot]

@copilot resolve conflict (either merge or rebase is ok)

Conflict resolved by merging renovate/major-tailwindcss-monorepo into the feature branch. The merge updated dependencies from the base branch (@babel/runtime 7.26.10, @typescript-eslint 8.54.0, webpack 5.105.0) while preserving the Tailwind CSS v4 upgrade changes. Build and tests pass successfully. Commit: e4729e2

[hogashi]

@copilot again resolve conflicts

[Copilot]

@copilot again resolve conflicts

Conflicts resolved by merging the updated renovate/major-tailwindcss-monorepo base branch. Key changes merged:

• Updated @biomejs/biome from 1.9.4 to 2.3.14 (Biome v2 migration)
• Updated lint script to use new Biome v2 syntax (--write --unsafe)
• Incorporated tsconfig JSX transform updates
• Preserved @tailwindcss/cli addition

Build, TypeScript compilation, and linter all pass successfully. Commit: 14fb3ba