Revert "Move skills watcher to app-server" (#21460)

Reverts openai/codex#21287

codex-rs/core/src/state/service.rs

@@ -9,6 +9,7 @@ use crate::exec_policy::ExecPolicyManager;
 use crate::guardian::GuardianRejection;
 use crate::guardian::GuardianRejectionCircuitBreaker;
 use crate::mcp::McpManager;
+use crate::skills_watcher::SkillsWatcher;
 use crate::tools::code_mode::CodeModeService;
 use crate::tools::network_approval::NetworkApprovalService;
 use crate::tools::sandboxing::ApprovalStore;
@@ -58,6 +59,7 @@ pub(crate) struct SessionServices {
     pub(crate) skills_manager: Arc<SkillsManager>,
     pub(crate) plugins_manager: Arc<PluginsManager>,
     pub(crate) mcp_manager: Arc<McpManager>,
+    pub(crate) skills_watcher: Arc<SkillsWatcher>,
     pub(crate) agent_control: AgentControl,
     pub(crate) network_proxy: Option<StartedNetworkProxy>,
     pub(crate) network_approval: Arc<NetworkApprovalService>,