[BUG] Preview panel overlaps chat area in RTL (Hebrew) layout

Description

When using Claude Code Desktop with Hebrew (RTL) interface, the Preview panel overlaps the chat area instead of being docked in its own section on the side.

Environment

• OS: Windows 11 Home 10.0.26200
• Claude Code: Desktop app (Max plan)
• Language: Hebrew (RTL)

Steps to Reproduce

1. Use Claude Code Desktop with Hebrew system language / RTL text direction
2. Start a dev server via .claude/launch.json
3. Preview panel opens and overlaps the main chat area instead of docking to the side

Expected Behavior

Preview panel should dock to the right (or left) side of the chat, without overlapping the conversation.

Actual Behavior

Preview panel renders on top of the chat area, making both the chat and the preview difficult to use simultaneously.

Screenshot

!Preview overlap

(The preview panel covers the chat content instead of being positioned beside it)

Notes

• This is likely related to existing RTL issues (#30037, #30080, #30085, #24284)
• The panel positioning logic probably doesn't account for RTL layout direction
• Other RTL issues focus on text rendering; this is specifically about panel/layout positioning