chore: Remove unused utility modules and related test files

- Remove currency, logger, validation utilities, and base/test provider logic
- Delete associated tests and TypeScript definitions for deprecated modules
- Clean up exports in `src/utils` to reflect module removals

src/utils/logger.ts

@@ -1,113 +0,0 @@
-/**
- * Structured logging utilities for the billing plugin
- */
-
-export type LogLevel = 'debug' | 'error' | 'info' | 'warn'
-
-export interface LogContext {
-  [key: string]: unknown
-  amount?: number
-  currency?: string
-  customerId?: string
-  invoiceId?: string
-  paymentId?: string
-  provider?: string
-  refundId?: string
-  webhookId?: string
-}
-
-export interface Logger {
-  debug(message: string, context?: LogContext): void
-  error(message: string, context?: LogContext): void
-  info(message: string, context?: LogContext): void
-  warn(message: string, context?: LogContext): void
-}
-
-/**
- * Creates a structured logger with consistent formatting
- */
-export function createLogger(namespace: string = 'BILLING'): Logger {
-  const log = (level: LogLevel, message: string, context: LogContext = {}) => {
-    const timestamp = new Date().toISOString()
-    const logData = {
-      level: level.toUpperCase(),
-      message,
-      namespace,
-      timestamp,
-      ...context,
-    }
-
-    // Use console methods based on log level
-    const consoleMethod = console[level] || console.log
-    consoleMethod(`[${namespace}] ${message}`, logData)
-  }
-
-  return {
-    debug: (message: string, context?: LogContext) => log('debug', message, context),
-    error: (message: string, context?: LogContext) => log('error', message, context),
-    info: (message: string, context?: LogContext) => log('info', message, context),
-    warn: (message: string, context?: LogContext) => log('warn', message, context),
-  }
-}
-
-/**
- * Default logger instance for the plugin
- */
-export const logger = createLogger('BILLING')
-
-/**
- * Creates a provider-specific logger
- */
-export function createProviderLogger(providerName: string): Logger {
-  return createLogger(`BILLING:${providerName.toUpperCase()}`)
-}
-
-/**
- * Log payment operations with consistent structure
- */
-export function logPaymentOperation(
-  operation: string,
-  paymentId: string,
-  provider: string,
-  context?: LogContext
-) {
-  logger.info(`Payment ${operation}`, {
-    operation,
-    paymentId,
-    provider,
-    ...context,
-  })
-}
-
-/**
- * Log webhook events with consistent structure
- */
-export function logWebhookEvent(
-  provider: string,
-  eventType: string,
-  webhookId: string,
-  context?: LogContext
-) {
-  logger.info(`Webhook received`, {
-    eventType,
-    provider,
-    webhookId,
-    ...context,
-  })
-}
-
-/**
- * Log errors with consistent structure
- */
-export function logError(
-  error: Error,
-  operation: string,
-  context?: LogContext
-) {
-  logger.error(`Operation failed: ${operation}`, {
-    error: error.message,
-    operation,
-    stack: error.stack,
-    ...context,
-  })
-}