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/Cargo.toml

@@ -74,6 +74,7 @@ codex-mcp-extension = { workspace = true }
 codex-model-provider = { workspace = true }
 codex-models-manager = { workspace = true }
 codex-protocol = { workspace = true }
+codex-queue-extension = { workspace = true }
 codex-app-server-protocol = { workspace = true }
 codex-app-server-transport = { workspace = true }
 codex-feedback = { workspace = true }