release: EQ Toolkit 2.0.0

[Maitrog]

Summary

This PR releases EQ Toolkit 2.0.0, migrates the extension to TypeScript and Vite, refreshes the interface, and introduces new user-facing features.

User-facing improvements

• Redesigned the popup interface:
  • grouped controls into clear sections;
  • added a compact equalizer enable/disable button with a visible active state;
  • added the current gain value in dB;
  • refreshed controls, checkboxes, settings, and modal styles.
• Added 13 built-in audio presets, including Bass Boost, Acoustic, Classical, Rock, and Pop.
• Added an option to hide built-in presets.
• Moved custom preset creation into a dedicated modal.
• Added validation for empty, duplicate, and reserved preset names.
• Improved window mode:
  • added spectrum visualization for the active tab;
  • added switching between captured tabs;
  • added the ability to stop audio capture for an individual tab.
• Added real-time spectrum visualization that responds to filter and settings changes.
• Added a localized onboarding guide shown after installation:
  • introduces themes, shortcuts, equalizer controls, volume, and presets;
  • highlights the relevant interface elements;
  • supports back, next, skip, and finish actions;
  • resumes when onboarding was not completed.
• Added Lao localization.
• Updated localization files.
• Added translator credits to the Community section.
• Added an uninstall feedback form.
• Removed the Christmas theme and its unused assets.

Architecture and build

• Migrated the background service worker, popup, content scripts, and toolkit window from JavaScript to TypeScript.
• Split the code into application, domain, UI, and infrastructure layers.
• Added typed modules for:
  • audio processing and equalizer state;
  • presets;
  • autostart rules;
  • keyboard shortcuts;
  • localization;
  • themes;
  • Chrome storage and runtime messages;
  • DOM access.
• Added strict TypeScript configuration.
• Added independent Vite builds for the background, popup, isolated content, and main content entry points.
• Added a build process that:
  • recreates dist;
  • copies the manifest, popup, resources, and localization files;
  • validates generated script bundles.
• Updated packaging to create the extension archive from dist.
• Removed obsolete JavaScript files and unused resources.
• Added Vitest unit tests.
• Added GitHub Actions test execution for pull requests and changes to main.
• Updated dependencies, .gitignore, localization validation, and development documentation.
• Added repository contribution guidelines in AGENTS.md.
• Removed the outdated Google Analytics statement from the privacy policy.

Verification

• npm test — 30 test files and 82 tests passed.
• npm run typecheck — passed.
• npm run lint:locales — passed for 19 locales.
• npm run build — production build completed successfully.

Scope

• 65 commits.
• 139 changed files.
• 12,329 additions and 3,777 deletions.