CREATE TABLE audit_log (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    timestamp INTEGER NOT NULL,
    user_id INTEGER,
    username TEXT NOT NULL DEFAULT '',
    action TEXT NOT NULL,
    target_type TEXT DEFAULT '',
    target_id TEXT DEFAULT '',
    details TEXT DEFAULT '',
    ip_address TEXT DEFAULT '',
    request_id TEXT DEFAULT ''
);
CREATE INDEX idx_audit_timestamp ON audit_log(timestamp);
CREATE INDEX idx_audit_action ON audit_log(action);