[BUG] "Send to Claude Code" shortcut does not maintain focus on Claude Code terminal (IntelliJ 2025.3)

Bug Description

The "Send to Claude Code" keyboard shortcut (Option+Cmd+K / claude-vscode.insertAtMention) in IntelliJ IDEA no longer maintains focus on the Claude Code terminal after execution.

Previously (IntelliJ 2025.1.2): The shortcut would:

1. Focus the Claude Code terminal
2. Insert the @-mention reference of the selected code/file
3. Maintain focus on the Claude Code terminal input — ready to type immediately

Currently (IntelliJ 2025.3): The shortcut:

1. Focuses the Claude Code terminal briefly
2. Inserts the @-mention reference correctly
3. Focus returns to the editor — user must manually click or use another shortcut to refocus

This breaks the workflow because users expect to immediately type their prompt after sending a reference.

Steps to Reproduce

1. Open a project in IntelliJ IDEA 2025.3
2. Start Claude Code in the terminal
3. Confirm IDE connection via /ide (shows "Connected to IntelliJ IDEA ✔")
4. Open any file in the editor and optionally select some code
5. Press Option+Cmd+K ("Send to Claude Code")
6. Observe that the reference is added but focus returns to the editor

Expected Behavior

After pressing Option+Cmd+K, focus should remain on the Claude Code terminal input so the user can immediately type their prompt.

Environment Info

• Platform: macOS (Darwin 25.2.0, Apple Silicon)
• IDE: IntelliJ IDEA 2025.3
• Claude Code CLI: 2.1.31
• Claude Code JetBrains Plugin: 0.1.14-beta
• IDE Connection: Confirmed working (/ide shows connected)

Additional Context

• This worked correctly in IntelliJ IDEA 2025.1.2 with the same plugin.
• The IDE connection is verified and functional — the issue is specifically about focus management after the shortcut execution.
• Possibly related to focus behavior changes made after #9765 (diff tab focus stealing fix), which may have inadvertently affected the "Send to Claude Code" focus retention.