chore: add CLAUDE.md

[vreshch]

Summary

• Adds project-specific CLAUDE.md for Claude Code guidance
• Covers Next.js 15 App Router architecture, Tailwind v4 patterns, and Docker deployment
• References root and showcase CLAUDE.md for shared standards

Test plan

• Verify content accuracy against current repo structure

[github-actions]

🎉 PR Validation ✅ PASSED

Commit: e0b3080b0325e29430f61b1755df98aa92eceaef
Branch: chore/add-claude-md

Checks:

• ✅ Dependencies installed
• ✅ Linting passed
• ✅ Format check passed
• ✅ Build successful
• ✅ Docker build
• ✅ E2E tests

Visual Changes: 5 of 20 screenshots changed

📸 downloads dark desktop — 100% changed

📸 downloads dark mobile — 100% changed

📸 downloads light desktop — 100% changed

📸 downloads light mobile — 100% changed

📸 home dark mobile — 1.222% changed

Before	After	Diff

Ready to merge! ✨

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⏰ Generated at: 2026-04-08T21:28:22.907Z