feat: fix: WebSocket 切断問題を修正 (Closes #23)

[LaphoqueRC]

Description

Created a dedicated WebSocketManager class to handle connection lifecycle, reconnection logic, and keepalive mechanism, replacing the existing ad-hoc WebSocket handling in the client.

Closes #23

Payout Wallet

SOL: HZV6YPdTeJPjPujWjzsFLLKja91K2Ze78XeY8MeFhfK8
ETH: 0x010A63e7Ee6E4925d2a71Bc93EA5374c9678869b
RTC: RTC2fe3c33c77666ff76a1cd0999fd4466ee81250ff
TON: UQC3yiapHm9Y7o06eFJq_emW_BjTUnPMYuqeAacTJw_uXiQe

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Style/UI update
• Code refactoring
• Performance improvement
• Test addition/update

What Was Built

• src/websocket/manager.ts
• src/websocket/types.ts
• src/moltlaunch/client.ts
• test/websocket.test.ts

Checklist

• Code is clean and follows the issue spec exactly
• One PR per bounty (no multiple bounties in one PR)
• Tests included for new functionality
• All existing tests pass
• No console.log or debugging code left behind
• No hardcoded secrets or API keys

Testing

• Manual testing performed
• Unit tests added/updated
• Integration tests added/updated

additional testing: 7 tests pass covering connection management, reconnection backoff, keepalive functionality, timeout detection, cleanup, and error scenarios. Verified single reconnection per disconnect and proper listener cleanup.