string together input editor + input / output + scrolling

[harryalbert]

Description

Linked Issue

• The linked issue is labeled ready-to-spec or ready-to-implement.
• Where appropriate, screenshots or a short video of the implementation are included below (especially for user-visible or UI changes).

Testing

• I have manually tested my changes locally with ./script/run

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[harryalbert]

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• get tool calls working #12849
• string together input editor + input / output + scrolling #12827 👈 (View in Graphite)
• add tech spec #12794
• Prototype TUI #12786
• warpui_core(tui): add ratatui-backed TUI presenter and runtime #12759
• warpui_core(tui): build TUI element primitives on ratatui-core #12758
• warpui_core: TUI element library (text, column, container, child_view, event_handler) #12634 : 1 other dependent PR (#12601 )
• Add TUI API surface to AppContext under tui #12633
• warpui_core: backend-neutral view hierarchy for a shared responder chain #12413 : 1 other dependent PR (#12414 )
• master

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