Added an AI disclosure notice to the public chat

The hosted public page and the web embed now show a short line ("You're chatting with an AI assistant.") as the very first thing in the conversation, before your agent's welcome message. It's there to meet Article 50(1) of the EU AI Act, which requires telling people they're talking to an AI, in effect from 2 August 2026.

The notice is a fixed divider, not a message: it can't be edited per agent, isn't sent to the model, and isn't saved to the conversation transcript. It shows on both public surfaces (the hosted page and the embed) regardless of how the conversation starts. It does not appear in the dashboard playground or in a conversation's read-only transcript.

The wording is a placeholder. The current copy ("You're chatting with an AI assistant" / "Vous échangez avec un assistant IA" / "Sie chatten mit einem KI-Assistenten.") is a deliberately generic first pass (it doesn't mention your brand name), pending sign-off on the final legal text. Expect it to change before the 2 August 2026 deadline.