[2 of 4] tui: route app and skill enablement through app server (#22914)

## Why
App and skill toggles are user config mutations too. When the TUI is
attached to a remote app server, writing those toggles into the local
`config.toml` makes the UI report success without updating the server
that actually owns the session.

This is **[2 of 4]** in a stacked series that moves TUI-owned config
mutations onto app-server APIs.

## What changed
- Routed app enable/disable persistence through app-server config batch
writes.
- Routed skill enable/disable persistence through `skills/config/write`.
- Avoided refreshing local config from disk after these writes when the
TUI is connected to a remote app server.

## Config keys affected
- `apps.<app_id>.enabled`
- `apps.<app_id>.disabled_reason`
- `[[skills.config]]` entries keyed by `path`, with `enabled = false`
used for persisted disables

## Suggested manual validation
- Connect the TUI to a remote app server, disable an app, reconnect, and
confirm the app remains disabled from remote config rather than local
disk state.
- Re-enable the same app and confirm both `apps.<app_id>.enabled` and
`apps.<app_id>.disabled_reason` are cleared remotely.
- Disable a skill in the manage-skills UI and confirm a remote
`[[skills.config]]` disable entry appears.
- Re-enable that skill and confirm the disable entry is removed and the
effective enabled state updates without relying on local config reloads.

## Stack
1. [#22913](https://github.com/openai/codex/pull/22913) `[1 of 4]`
primary settings writes
2. [#22914](https://github.com/openai/codex/pull/22914) `[2 of 4]` app
and skill enablement
3. [#22915](https://github.com/openai/codex/pull/22915) `[3 of 4]`
feature and memory toggles
4. [#22916](https://github.com/openai/codex/pull/22916) `[4 of 4]`
startup and onboarding bookkeeping

codex-rs/tui/src/chatwidget/tests.rs

@@ -119,11 +119,7 @@ pub(super) use codex_app_server_protocol::TurnStatus as AppServerTurnStatus;
 pub(super) use codex_app_server_protocol::UserInput;
 pub(super) use codex_app_server_protocol::UserInput as AppServerUserInput;
 pub(super) use codex_app_server_protocol::WarningNotification;
-pub(super) use codex_config::AppRequirementToml;
-pub(super) use codex_config::AppsRequirementsToml;
 pub(super) use codex_config::ConfigLayerStack;
-pub(super) use codex_config::ConfigRequirements;
-pub(super) use codex_config::ConfigRequirementsToml;
 pub(super) use codex_config::RequirementSource;
 pub(super) use codex_config::types::ApprovalsReviewer;
 pub(super) use codex_config::types::Notifications;
@@ -178,7 +174,6 @@ pub(super) use insta::assert_snapshot;
 pub(super) use serde_json::json;
 #[cfg(target_os = "windows")]
 pub(super) use serial_test::serial;
-pub(super) use std::collections::BTreeMap;
 pub(super) use std::collections::HashMap;
 pub(super) use std::path::PathBuf;
 pub(super) use tempfile::NamedTempFile;