Reduce TUI zero-state animation CPU usage

[kevinyang372]

Description

Reduces the CPU cost of the TUI zero-state animation while preserving its original 66 ms (~15 FPS) visual cadence.

• Suspends animation repaint scheduling while the terminal is unfocused and resumes immediately on focus gain.
• Caches logo geometry, reuses projection buffers, and paints the starfield directly.
• Replaces generic stack composition in the zero state with a specialized direct compositor while preserving opaque-overlay semantics.
• Adds production-shaped Criterion benchmarks and rendering/focus regression coverage.

At 120×40, the retained-frame benchmarks improved by approximately 68% for the built-in logo and 73% for the ASCII logo. Larger terminal sizes showed greater savings.

Implementation plan: https://staging.warp.dev/drive/notebook/NHie0i2bcU6ge5gHne0EEC

Linked Issue

None.

Testing

• Manually tested the TUI locally with ./script/run-tui
• cargo nextest run -p warpui_core --features tui --no-fail-fast (559 passed, 7 skipped)
• cargo nextest run -p warp_tui --features test-util --no-fail-fast (947 passed)
• cargo clippy --workspace --exclude warp_completer --all-targets --tests -- -D warnings
• cargo clippy -p warp --all-targets --tests -- -D warnings
• cargo clippy -p warp_completer --all-targets --tests -- -D warnings
• ./script/format --check
• git diff --check

Agent Mode

• Warp Agent Mode - This PR was created via Warp's AI Agent Mode

CHANGELOG-TUI: Reduced CPU usage while the zero-state animation is active.

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@kevinyang372

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Overview

This PR reduces TUI zero-state animation CPU usage by retaining logo projection buffers, painting the starfield directly, replacing the generic zero-state stack with a specialized compositor, and suspending timed repaints while the terminal is unfocused.

Concerns

• For this user-facing TUI change, please attach terminal visual evidence demonstrating the zero-state still renders correctly and focus pause/resume works end to end. Per repo guidance, acceptable TUI evidence is a terminal transcript, a render_to_lines / TuiBuffer::to_lines snapshot diff, or a ./script/run-tui capture; the PR currently lists manual testing but does not attach a capture.

Verdict

Found: 0 critical, 1 important, 0 suggestions

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[kevinyang372]

• Reduce TUI zero-state animation CPU usage #14604 👈 (View in Graphite)
• master

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