feat(composer): allow switching Enter vs Shift+Enter to send

[musnows]

Summary

• Add a persisted composerSendKey setting (enter | shiftEnter) so users can choose whether Enter or Shift+Enter sends from the chat composer.
• Wire FloatingComposer hotkey handling and Settings → Basics UI to the new preference; the other key inserts a newline.
• Keep @ mention commit on Enter when the mention menu is open, and include the setting in settings migrate/export paths.

Changes

• Shared settings: type, normalize, domain ownership, IPC patch schema, defaults
• Renderer: settings control + i18n, live setting hook, composer keydown
• Tests/fixtures updated for the new required settings field

Tests

• npx vitest run src/shared/app-settings.test.ts src/shared/app-settings-domain.test.ts src/renderer/src/locales/locale-resources.test.ts src/renderer/src/components/settings-section-general.test.ts
• npm run typecheck
• Manual: Settings → Basics → switch send shortcut, verify Enter / Shift+Enter behavior in composer

Made with Cursor

[XingYu-Zhong]

Rebase + review

已把本 PR rebase 到最新 develop，并 force-push 到 musnows:codex/composer-send-key：

• 丢掉已合入的 electron-updater bump（develop / v0.2.31 已包含）
• 解决 app-settings-domain.ts 与 initialSetupCompleted 的冲突
• 补了一处行为缺口：底部 footer 快捷键提示会随 composerSendKey 切换（新增 composerShortcutShiftEnter）

审查结论：建议合入（功能有价值，实现也基本到位）

做得好的地方

• 设置贯通完整：AppSettingsV1 → normalize → IPC zod → settings store default → 导出/迁移 → Settings UI → FloatingComposer
• 默认仍是 enter，兼容现有习惯
• isComposerSendHotkey 排除了 meta/ctrl，避免和系统快捷键打架
• hook 监听 SETTINGS_CHANGED_EVENT，改设置后无需重启
• 多语言文案齐全

本地已验证

• vitest：app-settings / app-settings-domain / locale-resources / settings-section-general（128 passed）
• npm run typecheck 通过

残留小问题（不阻塞合入，可后续跟）

• placeholder / composerHint 等文案仍写死 “Shift+Enter 换行”，切到 shiftEnter 发送后文案可能略不一致；footer 提示已修好
• @ 文件提及仍用裸 Enter 确认（合理，且在 shiftEnter 发送模式下不会误发送）

CI 跑绿后即可合。

[XingYu-Zhong]

LGTM after rebase onto develop.

Verified locally: focused vitest (128) + typecheck. Default remains Enter-to-send; setting is persisted and applied live. Footer shortcut hint now follows the selected send key.

Residual non-blocking: some placeholders still hardcode Shift+Enter-for-newline copy.