fix db bootstrap script

init_prod.sql

@@ -130,13 +130,11 @@ CREATE TABLE IF NOT EXISTS conversation_participants (
 -- Messages table
 CREATE TABLE IF NOT EXISTS messages (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
-    conversation_id INTEGER NOT NULL,
     sender_id INTEGER NOT NULL,
     content TEXT NOT NULL,
     sent_at DATETIME,
     created_at DATETIME,
     updated_at DATETIME,
-    FOREIGN KEY (conversation_id) REFERENCES channels(id),
     FOREIGN KEY (sender_id) REFERENCES users(id)
 );