feat: Add plan features and gating middleware

[kofimokome]

Fixes #8

Depends on #11

[sourceant]

Code Review Summary

This PR adds subscription gating, Stripe integration via Cashier, and feature entitlement logic. It introduces a custom BillingCustomer model and middleware to protect routes based on plan features.

🚀 Key Improvements

• Implemented a structured Entitlements system via CloudEntitlements.php.
• Added comprehensive OpenAPI documentation for the new checkout endpoint.
• Integrated Stripe webhooks to handle cache busting when subscription status changes.

💡 Minor Suggestions

• Fix inconsistent spacing in CloudController.
• Move config(['cashier.model' => ...]) to a boot method or the cashier config file.

🚨 Critical Issues

• Removal of debug_backtrace in CloudEntitlements is highly recommended to avoid brittle logic.
• Sensitive Stripe IDs should be moved to .env.

[sourceant]

Review complete. See the overview comment for a summary.

[sourceant]

Sensitive IDs and configuration values should not be hardcoded in the config file. They should be loaded via env() to ensure environment-specific values and better security.

Suggested change

	'monthly_price_id'=>'plan_id', // from stripe
	'monthly_price_id' => env('STRIPE_MONTHLY_PRICE_ID'),

[sourceant]

Using debug_backtrace for business logic (idempotency) is highly fragile and a performance anti-pattern. If the job class is renamed or the call stack changes, token consumption will fail. Pass the messageId explicitly to the consume method instead.

Suggested change

	foreach (debug_backtrace(DEBUG_BACKTRACE_PROVIDE_OBJECT) as $frame) {
	// Pass message context explicitly in the consume signature if possible.
	return null;

[sourceant]

The foreign key references billing_customers, but the migration name suggests it's linked to the user_id. Ensure consistency with Laravel Cashier expectations where the billable model is typically the User model directly, or explicitly define the owner relationship.

Suggested change

	$table->foreignId('user_id')->constrained('billing_customers')->cascadeOnDelete();
	$table->foreignId('user_id')->constrained('users')->cascadeOnDelete();

[nfebe]

This seem to have same commits as #11... I am a bit confused just 11 has 1 extra commit.

[kofimokome]

@nfebe it depends on #11. so you would have to review #11 first before this one.
I also added in the description that it depends on #11.

[kofimokome]

it's not possible to work on this without the changes in #10 (stripe integration) and #11 (entitlements integration)