fix: add constraint on status

Signed-off-by: Baptiste Bronsin <baptiste.bronsin@outlook.com>

Author: baptistebronsin

core/migrations/20251107091121_create_friend_requests_table.up.sql

@@ -2,7 +2,7 @@
 CREATE TABLE friend_requests (
     user_id_requested UUID NOT NULL,
     user_id_invited UUID NOT NULL,
-    status SMALLINT DEFAULT 0 NOT NULL,
+    status SMALLINT DEFAULT 0 NOT NULL CHECK (status IN (0, 1)), -- 0: pending, 1: declined
     created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP NOT NULL,
     PRIMARY KEY (user_id_requested, user_id_invited)
 );