chore(install): enforce interpreter-bound pip usage

[ShuhaoZhangTony]

Background

安装链路出现过解释器漂移（pip 与当前 conda python 不一致），导致包装到错误环境。

Scope

统一 Studio 安装入口，强制解释器绑定（python -m pip）并完善可观测性。

Tasks

• quickstart/install 脚本中移除裸 pip 调用
• 启动/安装阶段输出 sys.executable
• 文档补充：推荐命令始终使用 python -m pip

Acceptance Criteria

• 快速安装全程只调用当前解释器对应 pip
• which python、which pip、python -m pip --version 前缀一致
• 无“安装成功但当前环境找不到包”的复现

[ShuhaoZhangTony]

The concrete fix is prepared in PR #50.

It binds installation to one selected Python interpreter across quickstart, documentation, and CI, reports sys.executable, and adds regression guardrails against bare pip install. The issue will close automatically when the PR merges; the placeholder assignment is removed in the meantime.