db: refresh_sessions migration + SQLite/Postgres adapters

crates/adapters/postgres/migrations/0027_refresh_sessions.sql

@@ -0,0 +1,10 @@
+CREATE TABLE IF NOT EXISTS refresh_sessions (
+    id TEXT PRIMARY KEY,
+    user_id TEXT NOT NULL,
+    token TEXT NOT NULL UNIQUE,
+    expires_at TIMESTAMPTZ NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL
+);
+CREATE INDEX IF NOT EXISTS idx_refresh_sessions_token ON refresh_sessions(token);
+CREATE INDEX IF NOT EXISTS idx_refresh_sessions_user_id ON refresh_sessions(user_id);
+CREATE INDEX IF NOT EXISTS idx_refresh_sessions_expires_at ON refresh_sessions(expires_at);