[codex] Fix post-merge analytics integration failures (#27285)

## Why

Recent merges left `main` with analytics integration build failures.
Local Cargo runs also made the trimmed-skills test depend on
developer-installed skills, while Bazel used an isolated home.

## What changed

- Clone `thread_metadata.thread_source` when constructing goal analytics
event parameters.
- Group app-server thread extension inputs into
`ThreadExtensionDependencies`.
- Isolate the trimmed-skills test home so its exact fixture count is
stable across Cargo and Bazel.

## Validation

- `cargo check -p codex-analytics`
- `just test -p codex-analytics` (71 tests)
- `just test -p codex-app-server` (837 tests; one unrelated zsh-fork
timeout passed on retry)

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

@@ -26,19 +26,32 @@ use crate::outgoing_message::OutgoingMessageSender;
 use crate::thread_state::ThreadListenerCommand;
 use crate::thread_state::ThreadStateManager;
 
+pub(crate) struct ThreadExtensionDependencies {
+    pub(crate) event_sink: Arc<dyn ExtensionEventSink>,
+    pub(crate) auth_manager: Arc<AuthManager>,
+    pub(crate) state_db: Option<StateDbHandle>,
+    pub(crate) analytics_events_client: AnalyticsEventsClient,
+    pub(crate) thread_manager: Weak<ThreadManager>,
+    pub(crate) goal_service: Arc<GoalService>,
+    pub(crate) executor_skill_provider: Arc<dyn codex_skills_extension::SkillProvider>,
+}
+
 pub(crate) fn thread_extensions<S>(
     guardian_agent_spawner: S,
-    event_sink: Arc<dyn ExtensionEventSink>,
-    auth_manager: Arc<AuthManager>,
-    state_db: Option<StateDbHandle>,
-    analytics_events_client: AnalyticsEventsClient,
-    thread_manager: Weak<ThreadManager>,
-    goal_service: Arc<GoalService>,
-    executor_skill_provider: Arc<dyn codex_skills_extension::SkillProvider>,
+    dependencies: ThreadExtensionDependencies,
 ) -> Arc<ExtensionRegistry<Config>>
 where
     S: AgentSpawner<StartThreadOptions, Spawned = NewThread, Error = CodexErr> + 'static,
 {
+    let ThreadExtensionDependencies {
+        event_sink,
+        auth_manager,
+        state_db,
+        analytics_events_client,
+        thread_manager,
+        goal_service,
+        executor_skill_provider,
+    } = dependencies;
     let mut builder = ExtensionRegistryBuilder::<Config>::with_event_sink(event_sink);
     if let Some(state_db) = state_db {
         codex_goal_extension::install_with_backend(