feat: add billing plan foundations and refresh LocaleScope pricing

Introduce a shared pricing and entitlement model so plan metadata can drive public pricing and future subscription enforcement. Rebrand the product to LocaleScope and align the UI copy around market intelligence and business research workflows.

shared/types.ts

@@ -1,3 +1,5 @@
+import type { BillingInterval, PlanCode } from './billing/plans.js';
+
 export type JobStatus = 'pending' | 'running' | 'completed' | 'failed' | 'stopped';
 
 export interface AppUser {
@@ -30,9 +32,12 @@ export interface AccountSummary {
   totalBusinesses: number;
 }
 
-export interface AccountBillingPlaceholder {
-  status: 'not_configured';
-  planName: string | null;
+export type AccountBillingStatus = 'not_configured' | 'inactive' | 'active' | 'past_due' | 'canceled';
+
+export interface AccountBillingState {
+  status: AccountBillingStatus;
+  planCode: PlanCode | null;
+  billingInterval: BillingInterval | null;
   message: string;
 }
 
@@ -45,7 +50,7 @@ export interface AccountPageData {
   profile: AppUser;
   workspace: AccountWorkspace;
   summary: AccountSummary;
-  billing: AccountBillingPlaceholder;
+  billing: AccountBillingState;
   team: AccountTeamPlaceholder;
 }