fix(tui): highlight queued prompts on hover

[kitlangton]

What

Adds a subtle raised background when the queued-prompts dock is hovered, making its existing click behavior discoverable.

Before / After

Before: The queued-prompts dock looked identical at rest and under the pointer, so it did not read as interactive.

After: Hovering raises the dock background using the existing elevated theme treatment. Clicking still opens the queued-prompts manager.

How

• Tracks hover state in QueuedPromptDock.
• Uses theme.raise(theme.background.default) while hovered.
• Preserves the existing full-dock click target and layout.

Scope

This only changes the V2 TUI queued-prompts dock hover styling.

Testing

• bun typecheck from packages/tui
• Full repository pre-push typecheck (41 packages)
• OpenCode Drive end-to-end capture against this worktree

Demo

OpenCode Drive capture with a seeded simulated queued prompt. The dock starts at its default background, raises visibly for two seconds on hover, then opens the matching Queued prompts dialog on click.

queued-hover-final.mp4