feat(frontend): add shared client libraries and UI primitives

Introduce API helpers, types, hooks, design-system components, and the authenticated app shell.

frontend/src/components/ui/progress.tsx

@@ -0,0 +1,38 @@
+"use client";
+
+import * as React from "react";
+import { cn } from "@/lib/utils";
+
+interface ProgressProps extends React.HTMLAttributes<HTMLDivElement> {
+  value?: number;
+  gradient?: boolean;
+  /** Softer fill motion for verified-watch / long jumps. */
+  smooth?: boolean;
+}
+
+const Progress = React.forwardRef<HTMLDivElement, ProgressProps>(
+  ({ className, value = 0, gradient, smooth, ...props }, ref) => {
+    const pct = Math.min(100, Math.max(0, value));
+    return (
+      <div
+        ref={ref}
+        className={cn("relative h-2.5 w-full overflow-hidden rounded-full bg-muted", className)}
+        {...props}
+      >
+        <div
+          className={cn(
+            "h-full rounded-full will-change-[width] rtl:me-auto",
+            gradient ? "bg-primary" : "bg-primary",
+            smooth
+              ? "transition-[width] duration-1000 ease-[cubic-bezier(0.22,1,0.36,1)]"
+              : "transition-[width] duration-300 ease-out"
+          )}
+          style={{ width: `${pct}%` }}
+        />
+      </div>
+    );
+  }
+);
+Progress.displayName = "Progress";
+
+export { Progress };