问题标题：聊天历史记录管理缺陷 - 所有对话混入同一文件导致文件过大无法使用Issue Title: Chat History Management Defect - All Conversations Merged into Single File Causing Unusable File Size

[xiaoduanRobot]

问题描述：
Amazon Q 的聊天历史记录存在严重的管理问题：

所有聊天窗口共用一个 JSON 文件：无论打开多少个聊天窗口，所有对话都写入同一个 chat-history-xxx.json 文件，而不是为每个窗口创建独立文件

历史记录无限累积：每次发送消息时，插件会读取现有 JSON（包含所有历史记录），追加新消息后写回，导致文件不断膨胀，几次对话后就达到 10MB+

删除无效：即使手动删除 JSON 文件，只要不重启 IDE 继续对话，插件会从内存缓存中恢复所有历史记录并重新写入，文件瞬间又变回 10MB+

重启后仍恢复旧记录：即使重启 IDE，插件仍会从某处（可能是其他缓存文件）恢复之前的所有历史记录

我的尝试：

✗ 删除 JSON 文件 → 继续对话后立即恢复

✗ 设置文件为只读 → 可能创建新文件但问题依旧

✗ 重启 IDE → 历史记录仍被恢复

✓ 删除 JSON + 重启 IDE + 中途不发消息 → 唯一有效但极不方便

期待改善：

按聊天窗口分离文件：每个聊天窗口对应独立的 JSON 文件

文件大小限制：单个历史文件设置大小上限（如 1MB），超过后自动清理旧记录

提供历史管理选项：在设置中添加：

禁用历史记录保存

设置保留天数/条数

手动清除历史记录按钮

优化存储结构：不要每次都读取并写回完整历史，使用增量追加方式

影响：

文件过大导致读取失败

无法查看不同对话的独立历史

必须频繁手动清理才能正常使用

Description:
Amazon Q's chat history management has critical issues:

All chat windows share one JSON file: Regardless of how many chat windows are opened, all conversations are written to the same chat-history-xxx.json file instead of creating separate files per window

Unlimited history accumulation: When sending messages, the plugin reads the existing JSON (containing all history), appends new messages, and writes back, causing the file to bloat to 10MB+ after just a few conversations

Deletion ineffective: Even after manually deleting the JSON file, if you continue chatting without restarting the IDE, the plugin restores all history from memory cache and rewrites it, instantly returning to 10MB+

History restored after restart: Even after restarting the IDE, the plugin still restores all previous history from somewhere (possibly other cache files)

My Attempts:

✗ Delete JSON file → Immediately restored when continuing conversation

✗ Set file as read-only → May create new file but issue persists

✗ Restart IDE → History still restored

✓ Delete JSON + Restart IDE + Don't send messages during process → Only effective method but extremely inconvenient

Expected Improvements:

Separate files per chat window: Each chat window should have its own independent JSON file

File size limit: Set maximum size for history files (e.g., 1MB), automatically clean old records when exceeded

Provide history management options: Add settings for:

Disable history saving

Set retention days/message count

Manual clear history button

Optimize storage structure: Don't read and rewrite complete history every time, use incremental append approach

Impact:

Oversized files cause read failures

Cannot view independent history for different conversations

Must frequently manually clean to use normally