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/ui/dialog.tsx

@@ -5,6 +5,7 @@ import * as DialogPrimitive from "@radix-ui/react-dialog"
 import { XIcon } from "lucide-react"
 
 import { cn } from "@/lib/utils"
+import { useLanguage } from "@/lib/i18n"
 
 function Dialog({
   ...props
@@ -54,6 +55,7 @@ function DialogContent({
 }: React.ComponentProps<typeof DialogPrimitive.Content> & {
   showCloseButton?: boolean
 }) {
+  const { t } = useLanguage()
   return (
     <DialogPortal data-slot="dialog-portal">
       <DialogOverlay />
@@ -72,7 +74,7 @@ function DialogContent({
             className="ring-offset-background focus:ring-ring data-[state=open]:bg-accent data-[state=open]:text-muted-foreground absolute top-4 end-4 rounded-xs opacity-70 transition-opacity hover:opacity-100 focus:ring-2 focus:ring-offset-2 focus:outline-hidden disabled:pointer-events-none [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-4"
           >
             <XIcon />
-            <span className="sr-only">Close</span>
+            <span className="sr-only">{t("common.close")}</span>
           </DialogPrimitive.Close>
         )}
       </DialogPrimitive.Content>