fix(terminal): detect macOS PTY controller disconnects

[owainlewis]

The macOS disconnect monitor requested no poll events, so it missed PTY controller closure.
The editor usually exited later through a failed write, but slower startup exposed the broken monitor as a one-second disconnect timeout.
Request read events and throttle ordinary readiness without consuming input.
Use device identity to preserve /dev/tty exclusion and report classification errors before terminal setup.

Closes #175.
This fixes the terminal failure exposed by #174 without changing test deadlines.

Verification:

• A new real-PTY regression failed with the old mask (Continue instead of Disconnect) and passes with the fix.
• Input-preservation and descriptor-classification tests pass.
• cargo test: 322 unit tests pass, four existing performance tests ignored; eight of ten terminal tests pass locally.
• The two redirected-input tests fail under the local sandbox; both passed in the earlier GitHub run for fix(highlighting): restore TypeScript and Markdown syntax styles #174. Required CI must pass before merge.
• cargo fmt --check, all-target Clippy with warnings denied, and release build pass.
• Release PTY smoke: edit/undo, clean exit, unchanged file, restored terminal settings, and usable shell.

[greptile-apps]

Greptile Summary

The PR fixes macOS PTY controller-disconnect monitoring by requesting read readiness, throttling ordinary readable events without consuming input, and replacing terminal-name lookup with device-identity classification.

• Propagates descriptor-classification failures before terminal setup.
• Adds real-PTY coverage for controller hangups and input preservation.
• Documents the issue, implementation, and verification plan.

Confidence Score: 5/5

The PR appears safe to merge, assuming the required macOS CI checks pass.

The monitor prioritizes explicit disconnect events, preserves readable input, throttles repeated readiness, and includes focused tests for the corrected behavior; no concrete blocking or non-blocking issue remains.

Important Files Changed

Filename	Overview
src/terminal.rs	Updates terminal descriptor classification and polling behavior, with focused PTY regression tests; no actionable defect was established.
docs/issues/175-plan.md	Documents the disconnect-monitoring failure, intended fix, and acceptance criteria.

_{Reviews (1): Last reviewed commit: "fix(terminal): detect macOS PTY controll..." | Re-trigger Greptile}