initial agent setup

internal/db/sql/messages.sql

@@ -0,0 +1,30 @@
+-- name: GetMessage :one
+SELECT *
+FROM messages
+WHERE id = ? LIMIT 1;
+
+-- name: ListMessagesBySession :many
+SELECT *
+FROM messages
+WHERE session_id = ?
+ORDER BY created_at ASC;
+
+-- name: CreateMessage :one
+INSERT INTO messages (
+    id,
+    session_id,
+    message_data,
+    created_at,
+    updated_at
+) VALUES (
+    ?, ?, ?, strftime('%s', 'now'), strftime('%s', 'now')
+)
+RETURNING *;
+
+-- name: DeleteMessage :exec
+DELETE FROM messages
+WHERE id = ?;
+
+-- name: DeleteSessionMessages :exec
+DELETE FROM messages
+WHERE session_id = ?;