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/platform/login/page.tsx

@@ -0,0 +1,103 @@
+"use client";
+
+import { useState } from "react";
+import { signIn, getSession } from "next-auth/react";
+import { useRouter } from "next/navigation";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
+import { Alert, AlertDescription } from "@/components/ui/alert";
+
+export default function PlatformLoginPage() {
+  const [email, setEmail] = useState("");
+  const [password, setPassword] = useState("");
+  const [isLoading, setIsLoading] = useState(false);
+  const [error, setError] = useState("");
+  const router = useRouter();
+
+  const handleSubmit = async (e: React.FormEvent) => {
+    e.preventDefault();
+    setIsLoading(true);
+    setError("");
+
+    try {
+      const result = await signIn("credentials", {
+        email,
+        password,
+        redirect: false,
+        callbackUrl: "/platform/dashboard",
+      });
+
+      if (result?.error) {
+        setError("Invalid credentials");
+      } else {
+        // Verify the session has platform access
+        const session = await getSession();
+        if (session?.user?.isPlatformUser) {
+          router.push("/platform/dashboard");
+        } else {
+          setError("Platform access required");
+        }
+      }
+    } catch (error) {
+      setError("An error occurred during login");
+    } finally {
+      setIsLoading(false);
+    }
+  };
+
+  return (
+    <div className="min-h-screen flex items-center justify-center bg-gray-50 dark:bg-gray-900">
+      <Card className="w-full max-w-md">
+        <CardHeader className="text-center">
+          <CardTitle className="text-2xl font-bold">Platform Login</CardTitle>
+          <p className="text-muted-foreground">
+            Sign in to the Notso AI platform management dashboard
+          </p>
+        </CardHeader>
+        <CardContent>
+          <form onSubmit={handleSubmit} className="space-y-4">
+            {error && (
+              <Alert variant="destructive">
+                <AlertDescription>{error}</AlertDescription>
+              </Alert>
+            )}
+
+            <div className="space-y-2">
+              <Label htmlFor="email">Email</Label>
+              <Input
+                id="email"
+                type="email"
+                value={email}
+                onChange={(e) => setEmail(e.target.value)}
+                required
+                disabled={isLoading}
+              />
+            </div>
+
+            <div className="space-y-2">
+              <Label htmlFor="password">Password</Label>
+              <Input
+                id="password"
+                type="password"
+                value={password}
+                onChange={(e) => setPassword(e.target.value)}
+                required
+                disabled={isLoading}
+              />
+            </div>
+
+            <Button
+              type="submit"
+              className="w-full"
+              disabled={isLoading}
+            >
+              {isLoading ? "Signing in..." : "Sign In"}
+            </Button>
+          </form>
+        </CardContent>
+      </Card>
+    </div>
+  );
+}