Refactor persistent text streaming onto Stream core

CHANGELOG.md

@@ -1,5 +1,27 @@
 # Changelog
 
+## Unreleased
+
+- Require Convex 1.39 or newer.
+- Use `@convex-dev/stream` for all newly created streams while preserving
+  existing stream IDs and persisted text without a migration.
+- Keep every existing component, client, and React signature unchanged.
+- Add `readStream(ctx, streamId, streamArgs)` and the matching `useStream`
+  option. Expose it from an app-owned query so followers subscribe to bounded
+  append-only pages instead of re-reading the whole body on every append.
+  Authorize that query as you already authorize `getStreamBody`.
+- Elect one producer atomically; a duplicate drive request receives `205` and
+  reads durably instead of starting a second producer.
+- Bound persistence by time and bytes, serialize writes, and publish React text
+  at a fixed cadence.
+- Recover a failed drive connection through the same durable read, without
+  rewinding text already on screen.
+- Stop restarting the transport when an auth token rotates mid-stream.
+- Cap drive retries so a persistently failing endpoint falls back instead of
+  polling indefinitely.
+- Retain `getStreamBody` and the React query argument for apps that do not adopt
+  `readStream`.
+
 ## 0.3.3
 
 - Update ctx types for convex@1.41+