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/components/brainstorm/manual-idea-dialog.tsx

@@ -38,8 +38,8 @@ export function ManualIdeaDialog({
       <DialogContent className="sm:max-w-md bg-white dark:bg-[#1A1A1A] border-border rounded-2xl">
         <DialogHeader>
           <DialogTitle className="flex items-center gap-2 text-foreground">
-            <div className="w-7 h-7 rounded-lg bg-memento-blue/10 flex items-center justify-center">
-              <Lightbulb size={14} className="text-memento-blue" />
+            <div className="w-7 h-7 rounded-lg bg-brand-accent/10 flex items-center justify-center">
+              <Lightbulb size={14} className="text-brand-accent" />
             </div>
             <span className="font-serif">{t('brainstorm.addIdea') || 'Add an idea'}</span>
           </DialogTitle>
@@ -59,7 +59,7 @@ export function ManualIdeaDialog({
               value={title}
               onChange={(e) => setTitle(e.target.value)}
               placeholder={t('brainstorm.manualIdeaTitlePlaceholder') || 'Your idea in a few words...'}
-              className="w-full px-4 py-3 text-sm border border-border rounded-xl bg-transparent focus:outline-none focus:ring-2 focus:ring-memento-blue/20 focus:border-memento-blue/40 transition-all font-serif"
+              className="w-full px-4 py-3 text-sm border border-border rounded-xl bg-transparent focus:outline-none focus:ring-2 focus:ring-brand-accent/20 focus:border-brand-accent/40 transition-all font-serif"
               autoFocus
             />
           </div>
@@ -71,7 +71,7 @@ export function ManualIdeaDialog({
               value={description}
               onChange={(e) => setDescription(e.target.value)}
               placeholder={t('brainstorm.manualIdeaDescPlaceholder') || 'Elaborate on your idea...'}
-              className="w-full h-24 px-4 py-3 text-sm border border-border rounded-xl bg-transparent focus:outline-none focus:ring-2 focus:ring-memento-blue/20 focus:border-memento-blue/40 resize-none transition-all"
+              className="w-full h-24 px-4 py-3 text-sm border border-border rounded-xl bg-transparent focus:outline-none focus:ring-2 focus:ring-brand-accent/20 focus:border-brand-accent/40 resize-none transition-all"
             />
           </div>
           <div className="flex justify-end gap-2 pt-2">
@@ -85,7 +85,7 @@ export function ManualIdeaDialog({
             <button
               type="submit"
               disabled={!title.trim() || isLoading}
-              className="px-5 py-2.5 bg-memento-blue hover:bg-memento-blue text-white text-[10px] font-bold uppercase tracking-[0.15em] rounded-xl disabled:opacity-50 transition-all flex items-center gap-1.5"
+              className="px-5 py-2.5 bg-brand-accent hover:bg-brand-accent text-white text-[10px] font-bold uppercase tracking-[0.15em] rounded-xl disabled:opacity-50 transition-all flex items-center gap-1.5"
             >
               <Lightbulb size={12} />
               {isLoading ? (t('brainstorm.adding') || 'Adding...') : (t('brainstorm.addIdea') || 'Add idea')}