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>

app/api/rfm/dump_csv/route.ts

@@ -0,0 +1,13 @@
+import { NextResponse } from "next/server"
+import { dumpCsv } from "@/services/rfm-engine"
+
+export async function GET() {
+  const csv = dumpCsv()
+  return new NextResponse(csv, {
+    status: 200,
+    headers: {
+      "Content-Type": "text/csv; charset=utf-8",
+      "Content-Disposition": `attachment; filename="rfm_export_${Date.now()}.csv"`,
+    },
+  })
+}