Document baseURL validation in ai package changeset

Co-authored-by: Eric Allam <eric@trigger.dev>

Author: cursoragent

.changeset/curly-radios-visit.md

@@ -8,3 +8,4 @@ Add a new `@trigger.dev/ai` package with:
 - a typed `TriggerChatTransport` that plugs into AI SDK UI `useChat()` and runs chat backends as Trigger.dev tasks
 - rich default task payloads (`chatId`, trigger metadata, messages, request context) with optional payload mapping
 - reconnect-aware stream handling on top of Trigger.dev Realtime Streams v2
+- strict `baseURL` normalization/validation (trimming, path-safe slash handling, absolute `http(s)` URLs only, no query/hash/credentials)