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/connection.tsx

@@ -0,0 +1,28 @@
+import type { ConnectionLineComponent } from "@xyflow/react";
+
+const HALF = 0.5;
+
+export const Connection: ConnectionLineComponent = ({
+  fromX,
+  fromY,
+  toX,
+  toY,
+}) => (
+  <g>
+    <path
+      className="animated"
+      d={`M${fromX},${fromY} C ${fromX + (toX - fromX) * HALF},${fromY} ${fromX + (toX - fromX) * HALF},${toY} ${toX},${toY}`}
+      fill="none"
+      stroke="var(--color-ring)"
+      strokeWidth={1}
+    />
+    <circle
+      cx={toX}
+      cy={toY}
+      fill="#fff"
+      r={3}
+      stroke="var(--color-ring)"
+      strokeWidth={1}
+    />
+  </g>
+);