fix(conversation): preserve shortcuts and IME-safe multiline drafting

[PeterGuy326]

Supersedes #311 after rebuilding the change on the latest main.

Summary

• keep configurable send shortcuts while making Enter-send mode support Ctrl/⌘+Enter multiline insertion
• preserve Shift+Enter and IME composition safety
• retain the accepted → processing → completed progress interaction tests
• avoid all stale-file and packaging regressions from the original PR

Verification

• renderer: 553/553 tests passed
• renderer and UI typechecks passed
• renderer production build passed
• package layout/safety: 19/19 passed

[sun-970]

Review — Approve

Head cfbea72. MERGEABLE. Required CI on this head is green (Node 24 ubuntu/macOS, unsigned installers, unpacked smoke, layout parity, dependency review, Scorecard).

Enter-send mode: Ctrl/⌘+Enter inserts a newline at the caret (or replaces the selection) and restores the caret after the controlled value commits; a second chord uses the restored caret, not the end of the field. Same-value newline replacement (nextValue === value) updates the selection immediately. Conversation switches will not move another textarea (isConnected + value match).

Shift+Enter stays native. IME is ignored via composing ref + isComposing + keyCode 229, so confirmation neither sends nor inserts an extra line. mod-enter still sends on Ctrl/⌘+Enter; switching the preference on the same draft is covered. Send stays gated on trim / running / disabledReason.

Tests in turn-composer-shortcuts.test.tsx cover caret positions, selection replace, running-task drafting, shortcut preference, and IME. Progress interaction tests still cover accepted → processing → completed / failed / indeterminate.

Locales (en/zh) match the new chord. CHANGELOG [Unreleased] is present.

Non-blocking

• turn.keyboardHint is written for Enter-send mode. If the composer shows the same string in mod-enter mode, the copy is still slightly wrong (pre-existing shape).

Not a CODEOWNER.

[Bindy-lbb]

Review conclusion — no blocking issues found.\n\nI reviewed the 6-file diff covering TurnComposer, shortcut/progress tests, en/zh locales, and CHANGELOG. The Ctrl/⌘+Enter path preserves the caret after controlled-value commits, replaces selections correctly, keeps Shift+Enter native, and avoids dispatch during IME composition. I also checked running-task drafting, sendShortcut switching, and the existing progress interaction coverage.\n\nThe PR description reports green renderer tests/typechecks/build/package checks, and the focused shortcut/progress coverage is consistent with the implementation. One non-blocking copy caveat remains: the keyboard hint is specifically written for Enter-send mode; the existing mod-enter hint shape is outside this PR's scope. No blocking issue found; formal reviewer can proceed with the normal review flow.

[PeterGuy326]

在 exact head 080ae595f0f5af03fb874fb628b3c642e18605d2 上完成正式复核：未发现阻塞问题。

确认：

• Enter-send 模式下 Ctrl/⌘+Enter 在光标处插入换行，并正确替换选区、恢复受控 textarea 光标；连续触发不会跳到末尾。
• Shift+Enter 保持原生行为；IME 通过 composition ref、isComposing 和 keyCode 229 三层保护，不会误发送或多插入换行。
• mod-enter 模式仍由 Ctrl/⌘+Enter 发送；同一草稿切换 sendShortcut 后行为立即更新。
• running、disabledReason 和空白输入的发送门禁保持不变；进度交互覆盖 accepted → processing → completed/failed/indeterminate。

本地 exact-head 证据：npm run build、renderer typecheck 通过；目标 renderer 38 tests 全通过；git diff --check 通过。GitHub 当前 required checks 也为绿，且 PR 可合并。

非阻塞：keyboard hint 主要对应 Enter-send 模式；mod-enter 下的既有文案形态不在本 PR 范围内。

注：该 PR 作者是当前 GitHub 账号，GitHub 禁止作者自批，因此以正式 COMMENT review 提交；合并仍需非作者审批。

[PeterGuy326]

Content merged to main via #383 (in-repo recreation, rebase merge, commit authored as @PeterGuy326; all five file blobs byte-identical to this PR head). Closing because fork pull requests cannot satisfy the required CodeQL check name in branch protection on this repository. Original review history (approval by sun-970) preserved here.