V2 TUI: follow-up prompts should render optimistically

[opencode-agent]

Problem

Queued prompts/messages work, but the V2 TUI does not visibly show queued items or a queued indication like V1 did.

Expected behavior

When a prompt/message is queued behind an active run, the TUI should render it as pending/queued so the user knows it was accepted and will run later.

Actual behavior

The prompt/message is queued internally, but it is not visible in the TUI with a queued indication.

Scope notes

This is primarily a V2 TUI visibility/state-projection issue. It may require checking whether queued state is already exposed in the session/event stream or whether the TUI needs an explicit projected queued row/status.

[opencode-agent]

Additional context from Kit: queued messages should also render optimistically. Right now it can feel like there is a delay before the submitted message appears in the timeline.

This issue should cover both pieces of the queued-submit experience: a visible queued indication, and immediate/optimistic timeline rendering for accepted queued/submitted prompts.

[opencode-agent]

Tracker update from V2 TODO LIST discussion (2026-07-02):

Consensus:

• TUI default while a turn is running is steer, not queue.
• Current implementation slice should match V1 feel: submitted follow-up/steering prompts render immediately/optimistically in the timeline.
• Do not label steering submissions as Queued; reserve queued UI for explicit delivery: "queue" / future queue controls.
• Actual queue-management UI can be a later follow-up.

Source thread: https://discord.com/channels/1391832426048651334/1520962938733723720