Build temetro app: dark theme, clinical sidebar, AI chat, settings page

- Linear-inspired dark theme (app/globals.css), forced dark in layout
- Clinical sidebar (components/sidebar-02) with temetro brand
- AI chat UI (components/chat): Cursor-style input, UI-only mock replies
- Settings page (components/settings): Polar-style tabs/sections, UI only
- Route-group app shell: app/(app)/{layout,page,settings}
- shadcn (Base UI) + ai-elements component libraries
- CLAUDE.md: architecture notes + per-folder commit policy

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/components/ai-elements/node.tsx

@@ -0,0 +1,71 @@
+import {
+  Card,
+  CardAction,
+  CardContent,
+  CardDescription,
+  CardFooter,
+  CardHeader,
+  CardTitle,
+} from "@/components/ui/card";
+import { cn } from "@/lib/utils";
+import { Handle, Position } from "@xyflow/react";
+import type { ComponentProps } from "react";
+
+export type NodeProps = ComponentProps<typeof Card> & {
+  handles: {
+    target: boolean;
+    source: boolean;
+  };
+};
+
+export const Node = ({ handles, className, ...props }: NodeProps) => (
+  <Card
+    className={cn(
+      "node-container relative size-full h-auto w-sm gap-0 rounded-md p-0",
+      className
+    )}
+    {...props}
+  >
+    {handles.target && <Handle position={Position.Left} type="target" />}
+    {handles.source && <Handle position={Position.Right} type="source" />}
+    {props.children}
+  </Card>
+);
+
+export type NodeHeaderProps = ComponentProps<typeof CardHeader>;
+
+export const NodeHeader = ({ className, ...props }: NodeHeaderProps) => (
+  <CardHeader
+    className={cn("gap-0.5 rounded-t-md border-b bg-secondary p-3!", className)}
+    {...props}
+  />
+);
+
+export type NodeTitleProps = ComponentProps<typeof CardTitle>;
+
+export const NodeTitle = (props: NodeTitleProps) => <CardTitle {...props} />;
+
+export type NodeDescriptionProps = ComponentProps<typeof CardDescription>;
+
+export const NodeDescription = (props: NodeDescriptionProps) => (
+  <CardDescription {...props} />
+);
+
+export type NodeActionProps = ComponentProps<typeof CardAction>;
+
+export const NodeAction = (props: NodeActionProps) => <CardAction {...props} />;
+
+export type NodeContentProps = ComponentProps<typeof CardContent>;
+
+export const NodeContent = ({ className, ...props }: NodeContentProps) => (
+  <CardContent className={cn("p-3", className)} {...props} />
+);
+
+export type NodeFooterProps = ComponentProps<typeof CardFooter>;
+
+export const NodeFooter = ({ className, ...props }: NodeFooterProps) => (
+  <CardFooter
+    className={cn("rounded-b-md border-t bg-secondary p-3!", className)}
+    {...props}
+  />
+);