feat(wallpaper): add desktop keyboard chat input

[xijiangkiki]

What and why

Wallpaper mode may be used without voice interaction, while reopening the main Chat window can obscure the character and disrupt the wallpaper presentation. This adds a compact keyboard message input panel to Wallpaper mode, allowing users to continue chatting without returning to the main Chat window.

The panel opens by default in wallpaper mode and supports Enter to send, Shift + Enter for a new line, Esc to clear, a Send button, and a close/reopen toggle.

Linked issue: none

Change class

• Wallpaper UI feature

Owning layer: Wallpaper Electron Slice.

User-visible effect: Users can type and send messages directly from Wallpaper mode.

Compatibility or migration impact: none.

Evidence

Passed:

• Wallpaper input and session regression tests
• Local bridge security tests
• Electron npm test
• Electron npm run build
• git diff --check

Manual checks:

• Toggle works after switching focus to another application.
• Enter / Shift + Enter / Esc / Send button work as expected.
• Messages appear once in Main Chat.
• Existing conversations continue; an empty conversation list creates a new Chat.

Screenshots

Before

After

Expanded

Collapsed

Final check

• One coherent Wallpaper interaction improvement.
• No secrets, local sessions, models, voice material, or restricted assets included.

[Lucas1479]

Thanks @xijiangkiki — I support adding keyboard input to Wallpaper mode, and reusing the existing Chat/Session entry points is a good direction. CI is green, and I also ran the three related Python test files successfully (26 tests).

I reproduced two issues on e93218d that should be addressed before merging:

1. Confirmed speculative voice turns no longer produce a visible user message.
   The new chat.user event is emitted only when a turn starts with pending=False. confirm_pending_turn() does not emit it when a speculative turn is confirmed, while the previous wake-ASR message insertion has been removed from ChatPage. With send_text(..., source="wake", pending=True) followed by successful confirmation and stream completion, I observed zero chat.user events.
   Please cover both admission paths through the appropriate owner: an ordinary confirmed turn should emit once; a pending turn should emit once on successful confirmation; repeated confirmation must not duplicate it, and discarded turns must not display a user message.

2. Enter during IME composition submits the message.
   The composer keydown handler does not distinguish IME composition from a normal Enter press. In an event-level reproduction using the actual composer handler, an Enter event with isComposing=true and keyCode=229 still prevented the default action and triggered a send request. This can interfere with Chinese/Japanese candidate selection.
   Please add composition handling and executable keyboard-event tests: candidate confirmation must not send or clear the draft; ordinary Enter must send, and Shift+Enter must still insert a newline. The current source-string assertions and node --check do not exercise these behaviors.

Please make these changes in this PR and add the regression tests. The feature direction is supported; after these two issues are fixed and the checks pass, I can re-review it for merging.

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感谢 @xijiangkiki，我认可 Wallpaper 模式增加键盘输入的方向，复用现有 Chat／Session 入口也很合适。CI 已通过，我另外运行了相关的三个 Python 测试文件，26 项全部通过。

不过，在 e93218d 上额外复现了两处需要合并前修复的问题：

1. 投机语音确认后，主聊天会漏掉用户消息。
   新的 chat.user 只在 pending=False 的发送入口发出，confirm_pending_turn() 确认投机轮次时没有补发，而 ChatPage 原来的 wake-ASR 消息追加逻辑已经删除。实际调用 send_text(..., source="wake", pending=True)，再成功确认并等待流结束，收到的 chat.user 事件仍为 0。
   请在相应的生命周期所有者处覆盖两条路径：普通确认轮次显示一次；pending 轮次确认成功后显示一次；重复确认不重复显示；作废轮次不显示用户消息，并补回归测试。

2. 中文／日文输入法选词时按 Enter 会误发送。
   新输入框没有区分组合输入状态。在调用真实 composer 事件处理函数的复现中，isComposing=true、keyCode=229 的 Enter 事件仍然阻止了默认行为并发出发送请求。
   请补输入法组合输入处理和可执行的键盘事件测试：确认候选词不能发送或清空草稿；普通 Enter 仍能发送，Shift+Enter 仍能换行。当前的源码字符串断言和语法检查没有覆盖这些行为。

建议就在这条 PR 中完成这两处修复和回归测试。功能方向是认可的，修复并通过检查后，我再复核合并。

[xijiangkiki]

Addressed both review findings.

1. Pending speculative turns now emit chat.user exactly once after successful confirmation; discarded and repeated confirmations do not display duplicate user messages.
2. The Wallpaper keyboard composer now leaves IME composition events to the input method, with executable keyboard-event coverage for IME Enter, ordinary Enter, and Shift+Enter.

Validation:

• npm test
• npm run build
• tests/test_pending_turn.py
• tests/test_wallpaper_asset_revision.py
• tests/test_local_bridge_security.py

[Lucas1479]

Thank you @xijiangkiki for addressing both findings and adding executable regression coverage. I checked the latest fixes against the current mainline integration: all 28 related Python tests and the three keyboard-event tests passed, and all five CI checks are green. The speculative user-message lifecycle and IME candidate confirmation now address the issues from the previous review. Approved for merging.

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感谢 @xijiangkiki 完成两处修复，并补上可执行的回归测试。我已按当前主线的合并版本复核：28 项相关 Python 测试和 3 项键盘事件测试全部通过，五项 CI 也全绿。投机用户消息的确认／作废行为，以及输入法候选词确认，均已解决上一轮指出的问题。本次审核通过，准备合并。