feat(app-server): add remote control client management RPCs (#25785)

## Why

Remote-control clients need to list and revoke controller-device grants
without enabling or enrolling the local relay. These are signed-in
account-management operations, so coupling them to websocket, pairing,
enrollment, or persisted relay state would prevent clients from managing
stale grants from the picker.

Related enhancement request: N/A. This adds the Codex app-server surface
for the planned upstream environment-scoped revoke endpoint.

## What Changed

- Added experimental app-server v2 RPCs:
  - `remoteControl/client/list`
  - `remoteControl/client/revoke`
- Added picker-oriented protocol types and standard generated schema
fixtures. The list response intentionally omits backend account id,
enrollment status, and location fields.
- Added `app-server-transport/src/transport/remote_control/clients.rs`
for environment-scoped GET and DELETE requests. It builds escaped URL
path segments, forwards optional pagination query fields, sends ChatGPT
auth plus `chatgpt-account-id`, converts RFC3339 `last_seen_at` values
to Unix seconds, accepts `204 No Content` revoke responses, and retries
once after a `401`.
- Extracted shared ChatGPT auth loading and recovery into
`app-server-transport/src/transport/remote_control/auth.rs` so
websocket, pairing, and client management use the same account-auth
boundary.
- Retained the configured remote-control base URL on
`RemoteControlHandle` and resolve management URLs lazily, preserving
deferred validation while relay startup is disabled.
- Registered list as `global_shared_read("remote-control-clients")` and
revoke as `global("remote-control-clients")`.

## Verification

- Added transport coverage proving list and revoke work while relay
state is disabled, IDs are escaped, picker-only fields are returned,
timestamps are converted, revoke accepts `204`, auth headers are
forwarded, `401` retries exactly once, `403` is not retried, and
malformed list payloads retain decode context.
- Added an app-server integration test proving both JSON-RPC methods
work before relay enablement and successful revoke returns `{}`.
- Regenerated and validated experimental and standard app-server schema
fixtures.

codex-rs/app-server/src/message_processor.rs

@@ -922,6 +922,16 @@ impl MessageProcessor {
                 .pairing_start(params)
                 .await
                 .map(|response| Some(response.into())),
+            ClientRequest::RemoteControlClientsList { params, .. } => self
+                .remote_control_processor
+                .clients_list(params)
+                .await
+                .map(|response| Some(response.into())),
+            ClientRequest::RemoteControlClientsRevoke { params, .. } => self
+                .remote_control_processor
+                .clients_revoke(params)
+                .await
+                .map(|response| Some(response.into())),
             ClientRequest::ConfigRequirementsRead { params: _, .. } => self
                 .config_processor
                 .config_requirements_read()