fix: chat accepts quotes now

migrations/0051_quote_attachment.up.sql

@@ -0,0 +1,18 @@
+-- A shared passage from the library, sent into a chat.
+--
+-- Modelled as an attachment rather than message text so it can be rendered as
+-- a quote and navigated back to. It reuses the columns the link card already
+-- has, since the shape is the same thing said differently:
+--
+--   url         → the ?hl= deep link back to the exact phrase
+--   title       → the source reference ("Bhagavad-gītā 2.13")
+--   description → the quoted passage itself
+--
+-- It is a distinct kind rather than a 'link' because it renders as a quote,
+-- not a preview card, and because its URL is always our own — the service
+-- refuses any other origin.
+ALTER TABLE message_attachments DROP CONSTRAINT IF EXISTS message_attachments_kind_check;
+
+ALTER TABLE message_attachments
+    ADD CONSTRAINT message_attachments_kind_check
+    CHECK (kind IN ('image', 'video', 'audio', 'file', 'link', 'entity', 'quote'));