feat: release v0.2.0 profiles, chat, freeze, and bots

Ship the product pass on the v0.1.3 schema with additive migrations, a replica migration lock, and bot accounts kept out of people lists.

backend/internal/db/migrations/0026_username_change_quota.sql

@@ -0,0 +1,2 @@
+ALTER TABLE users ADD COLUMN IF NOT EXISTS username_change_count INTEGER NOT NULL DEFAULT 0;
+ALTER TABLE users ADD COLUMN IF NOT EXISTS username_cooldown_until TIMESTAMPTZ;