feat: add shared package with types and constants

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/shared/src/constants/plans.ts

@@ -0,0 +1,36 @@
+export const PLANS = {
+  starter: {
+    name: 'Starter',
+    cfdiLimit: 100,
+    usersLimit: 1,
+    features: ['dashboard', 'cfdi_basic', 'iva_isr'],
+  },
+  business: {
+    name: 'Business',
+    cfdiLimit: 500,
+    usersLimit: 3,
+    features: ['dashboard', 'cfdi_basic', 'iva_isr', 'reportes', 'alertas', 'calendario'],
+  },
+  professional: {
+    name: 'Professional',
+    cfdiLimit: 2000,
+    usersLimit: 10,
+    features: ['dashboard', 'cfdi_basic', 'iva_isr', 'reportes', 'alertas', 'calendario', 'conciliacion', 'forecasting', 'xml_sat'],
+  },
+  enterprise: {
+    name: 'Enterprise',
+    cfdiLimit: -1,
+    usersLimit: -1,
+    features: ['dashboard', 'cfdi_basic', 'iva_isr', 'reportes', 'alertas', 'calendario', 'conciliacion', 'forecasting', 'xml_sat', 'api', 'multi_empresa'],
+  },
+} as const;
+
+export type Plan = keyof typeof PLANS;
+
+export function getPlanLimits(plan: Plan) {
+  return PLANS[plan];
+}
+
+export function hasFeature(plan: Plan, feature: string): boolean {
+  return PLANS[plan].features.includes(feature);
+}