v3: chatbox improvements (typing indicators, answer to previous messages, backlog days separators, scroll to last message position, visual tweaks)

api/db/schema.sql

@@ -194,11 +194,12 @@ CREATE UNIQUE INDEX idx_notifications_dedup
   WHERE source_key IS NOT NULL;
 
 CREATE TABLE chat_messages (
-  id         TEXT NOT NULL PRIMARY KEY,
-  user_id    TEXT NOT NULL,
-  body       TEXT NOT NULL,
-  created_at TEXT NOT NULL,
-  updated_at TEXT,
+  id          TEXT NOT NULL PRIMARY KEY,
+  user_id     TEXT NOT NULL,
+  body        TEXT NOT NULL,
+  created_at  TEXT NOT NULL,
+  updated_at  TEXT,
+  reply_to_id TEXT,
   FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
 );
 CREATE INDEX idx_chat_messages_created ON chat_messages(created_at);