[BUG] AquaSKK: Ctrl+J and Kana key (keycode 0x68) not passed to IME for mode switching

Description

When using AquaSKK (a macOS SKK-based Japanese Input Method Editor) with Claude Code in iTerm2, the key combinations used to switch to Hiragana input mode are not passed to the IME.

Environment

• OS: macOS (Darwin 24.6.0)
• Terminal: iTerm2
• IME: AquaSKK
• Keyboard: US layout
• Claude Code version: 2.1 (latest)

Steps to Reproduce

1. Install AquaSKK as the Japanese IME
2. Open Claude Code in iTerm2
3. Try to switch to Hiragana mode using:

• Ctrl+J (default AquaSKK keybind for SKK_JMODE)
• Ctrl+Shift+J (alternative keybind added to keymap.conf)
• Kana key (keycode 0x68, simulated via Karabiner-Elements)

Expected Behavior

The key events should be passed to AquaSKK, triggering Hiragana input mode (SKK_JMODE).

Actual Behavior

• Ctrl+J: No effect in Claude Code (previously worked as newline in older versions, now does nothing)
• Ctrl+Shift+J: No effect in Claude Code
• Kana key (0x68): No effect in Claude Code

Note: All three methods work correctly in the normal iTerm2 shell outside of Claude Code.

Workarounds Attempted

1. AquaSKK keymap.conf: Added ctrl::shift::j to SKK_JMODE - works in shell, not in Claude Code
2. Karabiner-Elements: Mapped Ctrl+Shift+J to japanese_kana (keycode 0x68) for iTerm2 - works in shell, not in Claude Code
3. Hammerspoon eventtap: Key events are not captured when Claude Code is active
4. iTerm2 key mapping: Send Hex Code 0x68 - not passed to IME

Additional Context

• The l key for switching to ASCII mode in AquaSKK works fine
• This issue appeared after updating to Claude Code 2.1
• Other Japanese IME issues have been reported (#8405, #8466, #8423) but this specific AquaSKK/Ctrl+J issue seems unique

Request

Please ensure that Ctrl+J and Kana key (keycode 0x68) events are passed through to the system IME instead of being consumed by Claude Code.