Add durable user-message queue dispatch (#37204)

## What changed

- Add a storage-neutral queue extension for listing, adding, editing, reordering, deleting, and explicitly starting queued user messages.
- Dispatch queued messages in FIFO order when a thread becomes idle after a completed turn, while leaving them queued after interruptions or failures.
- Wait for user input to be persisted before removing its queue item, and report hook rejection, task termination, and persistence failures distinctly.
- Snapshot local image and audio attachments into validated data URLs before storing them, enforce input limits, and emit `ThreadQueueChanged` events after mutations.

## Testing

- Cover queue mutations, automatic and explicit dispatch, interruption and failure behavior, hook rejection, invalid records, input limits, and local attachment snapshotting.

GitOrigin-RevId: 14f39d7c8cbaccb767a6da84b82cced0edfcb4b9

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

@@ -66,6 +66,7 @@ use codex_chatgpt::workspace_settings;
 use codex_code_mode::CodeModeSessionProvider;
 use codex_core::ThreadManager;
 use codex_core::config::Config;
+use codex_core::config::ThreadStoreConfig;
 use codex_exec_server::EnvironmentManager;
 use codex_feedback::CodexFeedback;
 use codex_goal_extension::GoalService;
@@ -77,6 +78,8 @@ use codex_protocol::protocol::SessionSource;
 use codex_protocol::protocol::W3cTraceContext;
 use codex_rollout::StateDbHandle;
 use codex_state::log_db::LogDbLayer;
+use codex_thread_store::LocalQueueStore;
+use codex_thread_store::QueueStore;
 use tokio::sync::Mutex;
 use tokio::sync::Semaphore;
 use tokio::sync::broadcast;
@@ -247,6 +250,14 @@ impl MessageProcessor {
         // affect per-thread behavior, but they must not move newly started,
         // resumed, or forked threads to a different persistence backend/root.
         let thread_store = codex_core::thread_store_from_config(config.as_ref(), state_db.clone());
+        // Queue persistence requires SQLite, so in-memory thread stores and
+        // app servers without a state database do not have a queue backend.
+        let queue_store: Option<Arc<dyn QueueStore>> = match &config.experimental_thread_store {
+            ThreadStoreConfig::Local => state_db.as_ref().map(|state_db| {
+                Arc::new(LocalQueueStore::new(Arc::clone(state_db))) as Arc<dyn QueueStore>
+            }),
+            ThreadStoreConfig::InMemory { .. } => None,
+        };
         let environment_manager_for_requests = Arc::clone(&environment_manager);
         let environment_manager_for_extensions = Arc::clone(&environment_manager);
         let restriction_product = session_source.restriction_product();
@@ -281,7 +292,7 @@ impl MessageProcessor {
                         executor_skill_provider: Arc::clone(&executor_skill_provider),
                         git_attribution_base_url: config.chatgpt_base_url.clone(),
                         http_client_factory: config.http_client_factory(),
-                        thread_store: Arc::clone(&thread_store),
+                        queue_store,
                     },
                 ),
                 Arc::new(CodexHomeUserInstructionsProvider::new(