feat: design system overhaul — sidebar, AI chats, settings, brainstorm, color cleanup

- Sidebar: dynamic brand-accent colors, brainstorm section restyled
- AI chat general: popup panel with expand/collapse, hides when contextual AI open
- AI chat contextual: tabs reordered (Actions first), X close button, height fix
- Settings: all tabs restyled, 6 new color presets (sage, terracotta, iron, etc.)
- Global color cleanup: emerald/orange hardcoded → brand-accent dynamic
- Brainstorm page: orange → brand-accent throughout
- PageEntry animation component added to key pages
- Floating AI button: bg-brand-accent instead of hardcoded black
- i18n: all 15 locales updated with new AI/billing keys
- Billing: freemium quota tracking, BYOK, stripe subscription scaffolding
- Admin: integrated into new design
- AGENTS.md + CLAUDE.md project rules added

memento-note/app/(main)/agents/agents-page-client.tsx

@@ -2,6 +2,7 @@
 
 import { useState, useCallback, useMemo, useEffect, useRef } from 'react'
 import { motion } from 'motion/react'
+import { PageEntry } from '@/components/page-entry'
 import { Plus, Bot, Search, LifeBuoy } from 'lucide-react'
 import { toast } from 'sonner'
 import { useLanguage } from '@/lib/i18n'
@@ -204,6 +205,7 @@ export function AgentsPageClient({
   const showDetail = selectedAgent !== null || isNewAgent
 
   return (
+    <PageEntry>
     <>
       {showDetail ? (
         <AgentDetailView
@@ -332,5 +334,6 @@ export function AgentsPageClient({
         <AgentHelp onClose={() => setShowHelp(false)} />
       )}
     </>
+    </PageEntry>
   )
 }