feat: Add comprehensive test plan for Share Timer PWA

- Created TEST_PLAN.md outlining objectives, scope, test strategy, environments, and manual test suites.
- Included detailed test cases for smoke, functional, accessibility, localization, PWA, and regression guardrails.

feat: Document UI component designs for Share Timer

- Added UI_COMPONENTS.md detailing visual designs, key features, and implementation notes for components like Circular Countdown Timer, Timer Controls, Time Input, Settings Panel, Sound Selector, Volume Control, Language Toggle, and Notification Test Button.
- Included accessibility guidelines and responsive design considerations.

fix: Resolve critical UI/UX issues in Share Timer

- Updated UI_FIX_ANALYSIS_REPORT.md with findings from accessibility compliance checks and Tailwind CSS migration issues.
- Fixed button visibility, modal transparency, color contrast, and touch target sizes to meet WCAG 2.1 AA standards.
- Migrated color system to Tailwind v4, ensuring proper theme configuration and accessibility improvements.

Author: ryota-murakami

.gitignore

@@ -50,4 +50,6 @@ next-env.d.ts
 
 # playwright
 test-results
-playwright-report
+playwright-report
+
+claudedocs/screenshots

ICONS_NEEDED.md claudedocs/ICONS_NEEDED.mdICONS_NEEDED.md renamed to claudedocs/ICONS_NEEDED.md

@@ -28,18 +28,21 @@ The following icon files need to be added to the `/public` directory for the PWA
 ## Temporary Workaround
 
 The app will work without these icons, but:
+
 - Notifications will use browser default icons
 - PWA installation may not work on some devices
 - Icon references in manifest.ts should be updated once icons are added
 
 ## Creating Icons
 
 You can use tools like:
+
 - [PWA Asset Generator](https://github.com/elegantapp/pwa-asset-generator)
 - [RealFaviconGenerator](https://realfavicongenerator.net/)
 - Design tools: Figma, Sketch, Adobe Illustrator
 
 Example command using pwa-asset-generator:
+
 ```bash
 npx pwa-asset-generator logo.svg public --manifest app/manifest.ts
 ```