WebUI: thinking/reasoning blocks hidden after response completion, no way to show them

[hotic]

Problem

In the TUI, users can toggle thinking/reasoning blocks visibility with /thinking command (default: visible).

In the WebUI, thinking blocks are always hidden after response completion with no way to show them:

// session-turn.tsx:562
hideReasoning={!working()}  // hardcoded, no toggle

Expected Behavior WebUI should have the same /thinking command as TUI to toggle visibility.

Environment OpenCode version: latest dev Interface: WebUI