Update Chainlit config and UCB Library logos

* Set the meta URL to the Willa GitHub repository.

* Add a banner image for embeds.

* Update the UCB Library logo to the new version.

Closes: AP-551

Author: awilfox

.chainlit/config.toml

@@ -107,9 +107,10 @@ login_page_image = "/public/login-screen.png"
 # login_page_image_filter = "brightness-50 grayscale"
 # login_page_image_dark_filter = "contrast-200 blur-sm"
 
+custom_meta_url = "https://github.com/BerkeleyLibrary/willa"
 
 # Specify a custom meta image url.
-# custom_meta_image_url = "https://chainlit-cloud.s3.eu-west-3.amazonaws.com/logo/chainlit_banner.png"
+custom_meta_image_url = "/public/banner.png"
 
 # Load assistant logo directly from URL.
 logo_file_url = ""