feat: add optimistic locking and improve type safety

- Implement optimistic locking for deposit balance updates
  - Prevent race conditions in concurrent deposit requests
  - Add automatic retry with exponential backoff (max 3 attempts)
  - Add version column to user_deposits table

- Improve type safety across codebase
  - Add explicit types for Namecheap API responses
  - Add typed function arguments (ManageDepositArgs, etc.)
  - Remove `any` types from deposit-agent and tool files

- Add reconciliation job for balance integrity verification
  - Compare user_deposits.balance vs SUM(confirmed transactions)
  - Alert admin on discrepancy detection

- Set up test environment with Vitest + Miniflare
  - Add 50+ test cases for deposit system
  - Add helper functions for test data creation

- Update documentation
  - Add migration guide for version columns
  - Document optimistic locking patterns

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

src/types.ts

@@ -111,3 +111,212 @@ export interface BankNotification {
   transactionTime?: Date;
   rawMessage: string;
 }
+
+// Namecheap API 응답 타입
+export interface NamecheapPriceResponse {
+  tld: string;
+  krw: number;
+  usd?: number;
+  register_krw?: number;
+  renew_krw?: number;
+  transfer_krw?: number;
+}
+
+export interface NamecheapDomainInfo {
+  name: string;
+  created: string;
+  expires: string;
+  is_expired: boolean;
+  auto_renew: boolean;
+  is_locked: boolean;
+  whois_guard: boolean;
+  nameservers?: string[];
+}
+
+export interface NamecheapCheckResult {
+  [domain: string]: boolean;
+}
+
+export interface NamecheapDomainListItem {
+  name: string;
+  created: string;
+  expires: string;
+  is_expired: boolean;
+  auto_renew: boolean;
+  is_locked: boolean;
+  whois_guard: boolean;
+}
+
+// Function Calling 인자 타입
+export interface ManageDomainArgs {
+  action: 'register' | 'check' | 'whois' | 'list' | 'info' | 'get_ns' | 'set_ns' | 'price' | 'cheapest';
+  domain?: string;
+  nameservers?: string[];
+  tld?: string;
+}
+
+export interface ManageDepositArgs {
+  action: 'balance' | 'account' | 'request' | 'history' | 'cancel' | 'pending' | 'confirm' | 'reject';
+  depositor_name?: string;
+  amount?: number;
+  transaction_id?: number;
+  limit?: number;
+}
+
+export interface SuggestDomainsArgs {
+  keywords: string;
+}
+
+export interface SearchWebArgs {
+  query: string;
+}
+
+export interface LookupDocsArgs {
+  library: string;
+  query: string;
+}
+
+// Deposit Agent 결과 타입
+export interface DepositBalanceResult {
+  balance: number;
+  formatted: string;
+}
+
+export interface DepositAccountInfoResult {
+  bank: string;
+  account: string;
+  holder: string;
+  instruction: string;
+}
+
+export interface DepositRequestResult {
+  success: boolean;
+  auto_matched: boolean;
+  transaction_id: number;
+  amount: number;
+  depositor_name: string;
+  status?: string;
+  new_balance?: number;
+  message: string;
+  account_info?: {
+    bank: string;
+    account: string;
+    holder: string;
+  };
+}
+
+export interface DepositTransaction {
+  id: number;
+  type: string;
+  amount: number;
+  status: string;
+  depositor_name: string;
+  description: string | null;
+  created_at: string;
+  confirmed_at: string | null;
+}
+
+export interface DepositTransactionsResult {
+  transactions: DepositTransaction[];
+  message?: string;
+}
+
+export interface DepositCancelResult {
+  success: boolean;
+  transaction_id: number;
+  message: string;
+}
+
+export interface DepositPendingItem {
+  id: number;
+  amount: number;
+  depositor_name: string;
+  created_at: string;
+  user: string;
+}
+
+export interface DepositPendingResult {
+  pending: DepositPendingItem[];
+  message?: string;
+}
+
+export interface DepositConfirmResult {
+  success: boolean;
+  transaction_id: number;
+  amount: number;
+  message: string;
+}
+
+export interface DepositRejectResult {
+  success: boolean;
+  transaction_id: number;
+  message: string;
+}
+
+export interface DepositErrorResult {
+  error: string;
+}
+
+export type DepositFunctionResult =
+  | DepositBalanceResult
+  | DepositAccountInfoResult
+  | DepositRequestResult
+  | DepositTransactionsResult
+  | DepositCancelResult
+  | DepositPendingResult
+  | DepositConfirmResult
+  | DepositRejectResult
+  | DepositErrorResult;
+
+// Brave Search API 응답 타입
+export interface BraveSearchResult {
+  title: string;
+  description: string;
+  url: string;
+}
+
+export interface BraveSearchResponse {
+  web?: {
+    results: BraveSearchResult[];
+  };
+}
+
+// OpenAI API 응답 타입
+export interface OpenAIMessage {
+  role: string;
+  content: string;
+}
+
+export interface OpenAIChoice {
+  message: OpenAIMessage;
+}
+
+export interface OpenAIResponse {
+  choices?: OpenAIChoice[];
+}
+
+// Context7 API 응답 타입
+export interface Context7Library {
+  id: string;
+  name: string;
+}
+
+export interface Context7SearchResponse {
+  libraries?: Context7Library[];
+}
+
+export interface Context7DocsResponse {
+  context?: string;
+  content?: string;
+  message?: string;
+  error?: string;
+}
+
+// Telegram Inline Keyboard 데이터
+export interface DomainRegisterKeyboardData {
+  type: 'domain_register';
+  domain: string;
+  price: number;
+}
+
+export type KeyboardData = DomainRegisterKeyboardData;