[Stage 2 / P0] UX: first-run token modal + drop ?token= on first access

[modacker]

[Stage 2 / P0] UX: first-run token modal + drop ?token= on first access

Mirror of MiniMax-AI/MiniMax-Code-Plugins#25

This is the upstream-side mirror of the UX work tracked at MiniMax-AI/MiniMax-Code-Plugins#25.

实际修复在 plugins/Wzdhehe/mcode-webui/ 上游仓做。

范围

• 替换 stdout token 泄露
• first-run token modal
• drop ?token= on first access
• 估算 ~300 行

cc @Wzdhehe