Initial open source release

deploy/migrations/0060_user_last_seen.up.sql

@@ -0,0 +1,8 @@
+-- 0060_user_last_seen: persist exact last seen timestamps for UserStatusOffline.was_online.
+
+ALTER TABLE users
+    ADD COLUMN IF NOT EXISTS last_seen_at BIGINT NOT NULL DEFAULT 0;
+
+CREATE INDEX IF NOT EXISTS users_last_seen_idx
+    ON users (last_seen_at DESC)
+    WHERE last_seen_at > 0;