feat: implement platform management system with authentication and dashboard

- Add PlatformUser model with roles (SUPER_ADMIN, ADMIN, SUPPORT)
- Implement platform authentication with NextAuth
- Create platform dashboard showing companies, users, and sessions
- Add platform API endpoints for company management
- Update landing page with SaaS design
- Include test improvements and accessibility updates

app/api/platform/companies/route.ts

@@ -0,0 +1,99 @@
+import { NextRequest, NextResponse } from "next/server";
+import { getServerSession } from "next-auth";
+import { platformAuthOptions } from "../auth/[...nextauth]/route";
+import { prisma } from "../../../../lib/prisma";
+import { CompanyStatus } from "@prisma/client";
+
+// GET /api/platform/companies - List all companies
+export async function GET(request: NextRequest) {
+  try {
+    const session = await getServerSession(platformAuthOptions);
+
+    if (!session?.user?.isPlatformUser) {
+      return NextResponse.json({ error: "Platform access required" }, { status: 401 });
+    }
+
+    const { searchParams } = new URL(request.url);
+    const status = searchParams.get("status") as CompanyStatus | null;
+    const search = searchParams.get("search");
+    const page = parseInt(searchParams.get("page") || "1");
+    const limit = parseInt(searchParams.get("limit") || "20");
+    const offset = (page - 1) * limit;
+
+    const where: any = {};
+    if (status) where.status = status;
+    if (search) {
+      where.name = {
+        contains: search,
+        mode: "insensitive",
+      };
+    }
+
+    const [companies, total] = await Promise.all([
+      prisma.company.findMany({
+        where,
+        include: {
+          users: {
+            select: { id: true, email: true, role: true, createdAt: true },
+          },
+          _count: {
+            select: {
+              sessions: true,
+              imports: true,
+            },
+          },
+        },
+        orderBy: { createdAt: "desc" },
+        skip: offset,
+        take: limit,
+      }),
+      prisma.company.count({ where }),
+    ]);
+
+    return NextResponse.json({
+      companies,
+      pagination: {
+        page,
+        limit,
+        total,
+        pages: Math.ceil(total / limit),
+      },
+    });
+  } catch (error) {
+    console.error("Platform companies list error:", error);
+    return NextResponse.json({ error: "Internal server error" }, { status: 500 });
+  }
+}
+
+// POST /api/platform/companies - Create new company
+export async function POST(request: NextRequest) {
+  try {
+    const session = await getServerSession(platformAuthOptions);
+
+    if (!session?.user?.isPlatformUser || session.user.platformRole === "SUPPORT") {
+      return NextResponse.json({ error: "Admin access required" }, { status: 403 });
+    }
+
+    const body = await request.json();
+    const { name, csvUrl, csvUsername, csvPassword, status = "TRIAL" } = body;
+
+    if (!name || !csvUrl) {
+      return NextResponse.json({ error: "Name and CSV URL required" }, { status: 400 });
+    }
+
+    const company = await prisma.company.create({
+      data: {
+        name,
+        csvUrl,
+        csvUsername: csvUsername || null,
+        csvPassword: csvPassword || null,
+        status,
+      },
+    });
+
+    return NextResponse.json({ company }, { status: 201 });
+  } catch (error) {
+    console.error("Platform company creation error:", error);
+    return NextResponse.json({ error: "Internal server error" }, { status: 500 });
+  }
+}