feat: sync Sidebar and BottomNav, standardize user profile API

Align Sidebar & BottomNav menus, remove "Search", add user profile mock data, implement /api/users, add FilterDrawer, complete Section, ProfileHeader, MetricsRFM components

Co-authored-by: null <4804959+fnvtk@users.noreply.github.com>

components/rfm/rfm-badge.tsx

@@ -0,0 +1,15 @@
+import { Badge } from "@/components/ui/badge"
+
+export default function RfmBadge({ grade = "C" as const }: { grade: "S" | "A" | "B" | "C" | "D" }) {
+  const color =
+    grade === "S"
+      ? "bg-emerald-100 text-emerald-800"
+      : grade === "A"
+      ? "bg-green-100 text-green-800"
+      : grade === "B"
+      ? "bg-blue-100 text-blue-800"
+      : grade === "C"
+      ? "bg-amber-100 text-amber-800"
+      : "bg-red-100 text-red-800"
+  return <Badge className={color}>RFM {grade}</Badge>
+}