feat: initial commit

cmd/migrate/migrations/000006_add_followers_table.up.sql

@@ -0,0 +1,9 @@
+CREATE TABLE IF NOT EXISTS followers (
+    user_id bigint NOT NULL,
+    follower_id bigint NOT NULL,
+    created_at timestamp(0) with time zone NOT NULL DEFAULT NOW(),
+
+    PRIMARY KEY (user_id, follower_id),
+    FOREIGN KEY (user_id) REFERENCES users (id),
+    FOREIGN KEY (follower_id) REFERENCES users (id)
+);