feat(sdk): add SolanaSpendingLimits class to TypeScript SDK

Add TypeScript SDK integration for interacting with the mpc-spending-limit
Solana program.

SolanaSpendingLimits class provides:
- initialize(): Create spending config on-chain
- getState(): Fetch current config state
- getRemaining(): Get remaining allowance across periods
- validateTransfer(): Check if transfer is allowed (throws on violation)
- canTransfer(): Boolean check without throwing
- updateLimits(): Modify spending limits
- togglePause(): Pause/unpause config
- setGuardian(): Set emergency guardian
- addToWhitelist()/removeFromWhitelist(): Manage whitelist
- recordSpending(): Record completed transfer
- validateAndRecord(): Atomic validation + recording

Also includes:
- PDA derivation helpers
- State parsing from account data
- Base58 encoding/decoding utilities
- Network presets (Mainnet, Devnet, Testnet)
- Typed error codes for all spending limit violations

Author: Kazopl

packages/mpc-wallet-sdk/src/index.ts

@@ -75,6 +75,9 @@ export {
 // Chain adapters
 export * from './chains';
 
+// Solana spending limits
+export * from './solana';
+
 // Storage
 export * from './storage';
 

packages/mpc-wallet-sdk/src/solana/index.ts

@@ -0,0 +1,38 @@
+/**
+ * Solana-specific modules for MPC Wallet SDK
+ *
+ * This module provides Solana-specific functionality including:
+ * - Spending limits with on-chain enforcement
+ * - PDA-based configuration management
+ * - Whitelist/blacklist management
+ */
+
+export {
+  // Main class
+  SolanaSpendingLimits,
+
+  // Constants
+  MPC_SPENDING_LIMIT_PROGRAM_ID,
+  SPENDING_CONFIG_SEED,
+  WHITELIST_SEED,
+  SLOTS_PER_DAY,
+  SLOTS_PER_WEEK,
+  SLOTS_PER_MONTH,
+
+  // Network presets
+  SolanaLimitNetworks,
+
+  // Types
+  type SolanaNetwork,
+  type SpendingConfig,
+  type SpendingState,
+  type RemainingAllowance,
+  type WhitelistEntry,
+  type UpdateLimitsOptions,
+  type SolanaSpendingLimitsConfig,
+  type TransactionResult,
+
+  // Errors
+  SpendingLimitError,
+  SpendingLimitErrorCode,
+} from './spending-limit';