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/score/route.ts

@@ -0,0 +1,12 @@
+import { NextResponse } from "next/server"
+import { computeRFM, type AnalyzeInput } from "@/services/rfm-engine"
+
+export async function POST(req: Request) {
+  try {
+    const body = (await req.json()) as AnalyzeInput
+    const score = computeRFM(body)
+    return NextResponse.json({ success: true, data: score })
+  } catch (e: any) {
+    return NextResponse.json({ success: false, error: e?.message || "Invalid input" }, { status: 400 })
+  }
+}