[chore]: archive kt-sft package

[JimmyPeilinLi]

Message:

This PR moves the legacy kt-sft directory under archive/kt-sft so the active repository root only keeps the current v0.6.1 package layout.

Scope:

• Move kt-sft/ to archive/kt-sft/ with git mv.
• No file content changes.
• Documentation references are intentionally left unchanged for the follow-up documentation cleanup.

Validation:

• Pre-commit format hook passed; black was not installed and was skipped by the hook.
• GitHub PR checks passed.
• No runtime tests run because this is a pure archive move.

[gemini-code-assist]

Code Review

This pull request introduces a comprehensive set of files for the kt-sft project, including C++ backend extensions for CUDA and AMX, various model configurations for DeepSeek and Qwen, server API implementations for OpenAI and Ollama compatibility, and extensive optimization rules. I have no feedback to provide.