Apply Claude design system — warm parchment & terracotta palette

[rastermanden]

Summary

• Replaces the green color scheme with Anthropic's Claude design language
• All primary CTAs (save, confirm, auth button, add FAB) use Terracotta Brand (#c96442)
• Page background switches to Parchment (#f5f4ed), dark surfaces use Near Black (#141413)
• Ring-based shadows (0px 0px 0px 1px) throughout, replacing drop shadows
• Inter replaces DM Sans for body/UI text; Playfair Display kept for serif headings
• Focus states use Focus Blue (#3898ec) per accessibility spec
• Adds DESIGN.md — the Claude-inspired design system reference generated by npx getdesign@latest add claude

Test plan

• Auth screen: dark Near Black background, terracotta "Send magic link" button
• Header: dark background with terracotta FAB (+) button
• Bottom sheet / gem list: parchment background, warm card selection state
• Add gem modal: terracotta save button, blue focus rings on inputs
• Detail modal: dark emoji header, warm sand edit button, muted delete button
• Map markers: terracotta border on marker bubbles

🤖 Generated with Claude Code