fix: stop teardown drains at the first non-mouse event

[BinaryMuse]

Dogfooding atuin's eye-declare search surfaced this: all three teardown drains (async driver shutdown, init-exit shutdown, and the RawModeGuard drop fallback) read and discard every event type for up to 50ms, so keystrokes typed immediately after an app exits can be silently eaten.

The spray of stale mouse reports is contiguous, so the drain now stops at the first non-mouse event, leaving everything not yet read in the tty for the shell.

Correction from review: the cap is one crossterm buffer chunk, not one event. Crossterm reads the tty up to 1 KiB per syscall and queues every event it parses, so anything sharing a chunk with the first non-mouse event is consumed with it and cannot be handed back — ttys have no peek, and TIOCSTI is disabled on modern kernels. This PR is still a strict improvement (it stops all subsequent chunk reads, and the drain only continues through a dense spray — a 5ms gap ends it, so only keys typed into the spray are at risk), but a true byte-granular drain requires eye owning the input path instead of reading through crossterm. That design — which also addresses the CPR startup-latency and reader-thread-lock issues, with a PTY regression harness — is tracked as ATU-580.

[greptile-apps]

Greptile Summary

The PR improves terminal teardown by stopping mouse-report drains at the first non-mouse event, reducing the amount of user input consumed after application exit.

• Applies the behavior consistently to async shutdown, init-exit shutdown, and the RawModeGuard fallback.
• Documents crossterm’s chunk-buffering limitation.

Confidence Score: 5/5

The PR appears safe to merge with its remaining crossterm buffering limitation clearly documented.

The changed drains consistently stop after observing a non-mouse event, and no unacknowledged concrete failure was established.

Important Files Changed

Filename	Overview
crates/eye_declare/src/driver_tokio.rs	Updates async and pre-loop synchronous drains to continue only for mouse events.
crates/eye_declare/src/runtime.rs	Applies matching stop-on-non-mouse behavior to the drop-time fallback drain.

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