Add Paystack prepaid billing and fix sidebar footer spacing.

Monthly Pro/Enterprise stays on wallet; 6/12/24 month plans checkout via Paystack.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Services/Billing/BillingClient.php

@@ -61,4 +61,48 @@ class BillingClient
 
         return true;
     }
+
+    /**
+     * @param  array<string, mixed>  $metadata
+     * @return array{checkout_url: string, reference: string}
+     */
+    public function initiatePlanCheckout(
+        string $publicId,
+        string $plan,
+        int $months,
+        int $amountMinor,
+        string $returnUrl,
+        array $metadata = [],
+    ): array {
+        $res = Http::withToken($this->token())->acceptJson()->timeout(15)->post($this->base().'/plan-checkout', [
+            'user' => $publicId,
+            'app' => (string) config('billing.service', 'queue'),
+            'plan' => $plan,
+            'months' => $months,
+            'amount_minor' => $amountMinor,
+            'return_url' => $returnUrl,
+            'metadata' => $metadata,
+        ]);
+        $res->throw();
+
+        return [
+            'checkout_url' => (string) $res->json('checkout_url'),
+            'reference' => (string) $res->json('reference'),
+        ];
+    }
+
+    /** @return array<string, mixed> */
+    public function verifyPlanCheckout(string $reference): array
+    {
+        $res = Http::withToken($this->token())->acceptJson()->timeout(15)->post($this->base().'/plan-checkout/verify', [
+            'reference' => $reference,
+        ]);
+
+        if ($res->status() === 422) {
+            return ['paid' => false, 'error' => $res->json('error')];
+        }
+        $res->throw();
+
+        return $res->json();
+    }
 }