Preserve CJK IME typing

[ComputelessComputer]

Skip title navigation while composition is active and protect rich-editor content sync around IME composition.

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Note

Medium Risk
Touches focused-session title navigation and ProseMirror content replacement timing; wrong composition detection could delay sync or leave stale content, but scope is narrow and covered by new tests.

Overview
Fixes CJK/IME typing being interrupted when composition keys (e.g. Enter with keyCode 229) were treated as title navigation or when external note content sync ran mid-composition.

Session title: TitleInput now bails out of handleKeyDown during composition (isComposing, Process, keyCode 229), so confirming IME text no longer commits the title or jumps to the editor.

Note editor: Adds composition tracking via a ProseMirror plugin, getEditorCompositionWaitMs (500ms active + post-composition grace), and deferred syncContent retries so reconciledInitialContent updates do not replace the document while IME is active or immediately after it ends. Composition state resets on view dispose. Unit tests cover title IME Enter and the wait-window helper.

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[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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