## Why
Remote-control app-server enrollments have both an internal server id
and the environment id exposed to remote-control clients. App-server
clients need one current status snapshot that says whether remote
control is usable and which environment id, if any, is exposed.
A temporary websocket disconnect is not itself an identity change.
Account changes, stale enrollment invalidation, successful
re-enrollment, and missing ChatGPT auth are meaningful status changes.
Disabled remote control remains `disabled` regardless of auth or SQLite
state. SQLite startup failure disablement and enrollment persistence
failures are handled in #20068; this PR reports the resulting effective
status to clients.
## What changed
- Adds v2 `remoteControl/status/changed` carrying `state` and
`environmentId`.
- Adds `RemoteControlConnectionState` values: `disabled`, `connecting`,
`connected`, and `errored`.
- Exposes remote-control status updates through `RemoteControlHandle`
using a Tokio watch channel.
- Always sends the current remote-control status snapshot to newly
initialized app-server clients.
- Broadcasts status changes to initialized app-server clients when state
or environment id changes.
- Treats missing ChatGPT auth as an `errored` status while leaving it
retryable because auth can change at runtime.
- Clears `environmentId` when enrollment is cleared for account changes,
auth loss, stale backend invalidation, or disabled remote control.
- Updates app-server protocol schema fixtures, generated TypeScript,
app-server README, remote-control tests, and TUI exhaustive notification
matches.
## Stack
- Builds on #20068.
## Verification
- `just write-app-server-schema`
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-app-server transport::remote_control --lib`
- `cargo check -p codex-tui`
- `just fix -p codex-app-server-protocol`
- `just fix -p codex-app-server`
- `just fix -p codex-tui`
