Improve transcript copy and chat placement

[ComputelessComputer]

Summary:

• Add a direct copy action to the expanded transcript panel.
• Anchor the floating chat panel to the right side of the note surface.
• Cover both behaviors with focused desktop tests.

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Note

Medium Risk
Touches global chat mode, keyboard shortcuts, and main layout resizing across many surfaces; transcript copy uses the clipboard API but is localized UI behavior.

Overview
Adds a docked right-panel chat alongside the existing floating overlay, with a new RightPanelOpen mode and OPEN_RIGHT_PANEL transitions so users can move between float and dock from the toolbar.

The floating chat drops in-place “expand to fill anchor” behavior: it stays bottom-right on the note surface, resize math is updated, and the old maximize/collapse control is replaced by open in right panel / float chat actions. Escape, home navigation, the session Ask CTA, changelog, and transcript Esc handling now treat any open chat (floating or docked) consistently; switching sessions still collapses chat when leaving the current note.

Also adds Copy transcript on the expanded post-session panel (formatted export text → clipboard) with short-lived transient toasts, and fixes chat input text color on the white composer surface.

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

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