refactor: flatten monorepo structure to backend/ frontend/ devops/

Rename subdirectories for a cleaner single-repo layout:
- website-monitoring-backend/  → backend/
- website-monitoring-frontend/ → frontend/
- website-monitoring-devops/   → devops/

Update all references in package.json scripts, CI workflows,
docker-compose, pre-commit hooks, and documentation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/src/app/api/billing/usage/route.ts

@@ -0,0 +1,96 @@
+import { NextResponse } from "next/server";
+import { getSupabaseAdmin } from "@/lib/admin";
+import { TIER_LIMITS } from "@/services/tierLimits";
+import { requireOrgMembership } from "@/lib/apiAuth";
+
+/**
+ * GET /api/billing/usage
+ * 
+ * Returns current usage vs tier limits for an organization.
+ * Requires authenticated user who is a member of the organization.
+ * Query params: ?organizationId=xxx
+ */
+export async function GET(request: Request) {
+  try {
+    const url = new URL(request.url);
+    const organizationId = url.searchParams.get("organizationId");
+
+    if (!organizationId) {
+      return NextResponse.json({ error: "organizationId required" }, { status: 400 });
+    }
+
+    // Verify caller belongs to this organization
+    const auth = await requireOrgMembership(organizationId, request);
+    if (auth instanceof NextResponse) return auth;
+
+    const supabase = getSupabaseAdmin();
+
+    // Get organization with tier info
+    const { data: org, error: orgError } = await supabase
+      .from("organizations")
+      .select("id, name, subscription_tier, subscription_status, created_at")
+      .eq("id", organizationId)
+      .single();
+
+    if (orgError || !org) {
+      return NextResponse.json({ error: "Organization not found" }, { status: 404 });
+    }
+
+    const tier = String(org.subscription_tier || "free");
+    const limits = TIER_LIMITS[tier] || TIER_LIMITS.free;
+
+    // Get current usage (parallel queries)
+    const startOfMonth = new Date();
+    startOfMonth.setDate(1);
+    startOfMonth.setHours(0, 0, 0, 0);
+
+    const [
+      { count: websiteCount },
+      { count: memberCount },
+      { count: scanCountThisMonth },
+      { count: scanCountTotal },
+      { count: alertCount },
+    ] = await Promise.all([
+      supabase.from("websites").select("*", { count: "exact", head: true }).eq("organization_id", organizationId),
+      supabase.from("organization_members").select("*", { count: "exact", head: true }).eq("organization_id", organizationId),
+      supabase
+        .from("scans")
+        .select("*", { count: "exact", head: true })
+        .gte("created_at", startOfMonth.toISOString()),
+      supabase.from("scans").select("*", { count: "exact", head: true }),
+      supabase.from("alerts").select("*", { count: "exact", head: true }).eq("status", "active"),
+    ]);
+
+    const usage = {
+      websites: { used: websiteCount || 0, limit: limits.websites, percentage: limits.websites === -1 ? 0 : Math.round(((websiteCount || 0) / limits.websites) * 100) },
+      scansThisMonth: { used: scanCountThisMonth || 0, limit: limits.scansPerMonth, percentage: limits.scansPerMonth === -1 ? 0 : Math.round(((scanCountThisMonth || 0) / limits.scansPerMonth) * 100) },
+      teamMembers: { used: memberCount || 0, limit: limits.teamMembers, percentage: limits.teamMembers === -1 ? 0 : Math.round(((memberCount || 0) / limits.teamMembers) * 100) },
+      totalScans: scanCountTotal || 0,
+      activeAlerts: alertCount || 0,
+    };
+
+    return NextResponse.json({
+      organization: {
+        id: org.id,
+        name: org.name,
+        tier,
+        status: org.subscription_status || "active",
+        createdAt: org.created_at,
+      },
+      plan: limits,
+      usage,
+      features: {
+        scheduledScans: limits.scheduledScans,
+        alertNotifications: limits.alertNotifications,
+        competitorAnalysis: limits.competitorAnalysis,
+        apiAccess: limits.apiAccess,
+        prioritySupport: limits.prioritySupport,
+      },
+    });
+  } catch (error) {
+    return NextResponse.json(
+      { error: error instanceof Error ? error.message : "Unknown error" },
+      { status: 500 }
+    );
+  }
+}