feat(cli): Add optional Snake game to the init waiting screen

[sergical]

Summary

sentry init waits a long time on the remote setup workflow. This PR adds an optional Snake game to the waiting screen. Press g to play.

• The game engine (snake-game.ts) is pure state plus a half-block renderer. Each tick re-renders only the board.
• A prompt, a new warning or error, or the end of the run closes the game and pauses it.
• SENTRY_INIT_GAME=0 hides the game. It is also hidden when an AI agent runs the CLI.
• The pane is measured with useBoxMetrics. A resize pauses the run and keeps it.
• pnpm --filter sentry run proto:snake runs the UI against a fake, offline workflow.

Breaking Changes

• None

[cursor]

Stale Bugbot comment from a previous run.

[betegon]

Before merging:

• Stabilize the pane sizing in ink-app.tsx / ink-snake.tsx. At 80×20, pressing g then ↑ changes the measured board width and pauses the game before its first tick, without a terminal resize. Keep the score/help visible and add a regression covering narrow and wide terminals.
• Respect NO_COLOR in the renderer while keeping the cell types distinguishable.
• Add the required JSDoc for the new engine exports and type fields.

The engine/UI split and shared shortcuts fit the repo. Property/model-based tests would suit the engine invariants, but that preference is not a separate merge blocker.

[sergical]

@betegon Thanks for the review. Fixed in 0ea3fc8:

• Pane sizing: the left pane's width came from its content: the board plus the "Press an arrow key to start" hint. When ↑ cleared the hint, the pane width changed, resizeSnake ran, and the game paused before its first tick. While the game shows, the pane now has flexBasis={0}, so its content no longer sets its width. The status hint now has its own one-line row under the score, cut to fit, so the score and best score always stay visible. New regression tests at 80×20 and 160×50 check that the board border stays the same after the first ↑ and 400 ms later, that the score and footer stay visible, and that "Paused" never appears.
• NO_COLOR: renderSnake takes a color flag. ink-snake.tsx passes !isPlainOutput(), which covers NO_COLOR and SENTRY_PLAIN_OUTPUT. Without color, the board uses glyphs: @ head, o body, * food, space for empty cells. Tests cover the renderer and the Ink component.
• JSDoc: added to every exported engine symbol and type field in snake-game.ts, and to the exported types and components in ink-snake.tsx.
• Property tests: two fast-check tests in snake-game.test.ts. One checks that the snake stays on the board and never overlaps itself. The other checks that food never lands on the snake and that the body length is always 3 + score.

[linear-code]

DEVEX-752

[vercel]

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1 Skipped Deployment

Project	Deployment	Actions	Updated
sentry-local	Skipped		Oct 15, 2026 6:36pm UTC

[cursor]

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

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