feat(core): adding ide info to /completion route

[Sma1lboy]

This PR addresses part of the issue mentioned in #2581 by implementing server-side changes to extract and process IDE information from the User-Agent header.

Description:

• Server Getting Ide info from header's user-agent
• save ide info as json string

Example format of ide info:

{
    "name": "Visual Studio Code",
    "version": "1.91.1",
    "extensionName": "Tabby",
    "extensionPublisher": "TabbyML",
    "extensionVersion": "1.8.0-dev",
    "osType": "Darwin",
    "osRelease": "23.5.0",
    "platform": "darwin",
    "arch": "arm64"
}

[wsxiaoys]

cc @xxs-wallace

[wsxiaoys]

I recommend extract backend change (rust change) into a separate PR for review.

[wsxiaoys]

Otherwise LGTM