Summary

• Replace keyboard.json dialog-based editing (KeyboardJsonEditorDialog, LayoutPreviewDialog) with an integrated tab-based UI matching the keymap.c editor pattern
• Add three tabs for keyboard.json: Code Editor, Form Editor (vertical sub-tabs for General/USB・MCU/Hardware/Features/Lighting/Input), and Key Layout (visual drag editor)
• Implement 2-way binding with debounced auto-apply for both Form Editor and Key Layout — no more explicit Apply buttons
• Keep Code Editor always mounted (display:none) to preserve editing state and pending debounce across tab switches
• Show JSON parse error messages when switching to Form Editor or Key Layout with invalid JSON
• Add i18n entries for new UI labels (Form Editor, Could not parse keyboard.json.)

Test plan

• Select keyboard.json → verify 3 tabs appear (Code Editor / Form Editor / Key Layout)
• Edit keyboard name in Form Editor → switch to Code Editor → verify JSON reflects the change
• Switch back to Form Editor → verify the changed name is retained
• Break JSON in Code Editor (remove a comma) → switch to Form Editor → verify error message is shown
• Switch to Key Layout tab → verify error message is shown there too
• Switch back to Code Editor → verify the broken JSON is preserved (comma not restored)
• Fix JSON in Code Editor → switch to Form Editor → verify form loads correctly
• Drag a key in Key Layout → switch to Code Editor → verify layout positions updated in JSON
• Verify keymap.c tabs (Code Editor / Visual Editor) still work correctly
• Verify Japanese locale displays correctly for all new labels

🤖 Generated with Claude Code