fix: WS reconnection deadlock, remove redundant try/except, fix docs

- websocket.js: schedule reconnect backoff when token refresh fails,
  otherwise WebSocket stays dead after 3+ disconnects with failed refresh
- daemon/handlers/auth.py: remove two redundant try/except ValueError: raise
  blocks in webauthn register/authenticate finish handlers
- docs/api.md: mark permissions as optional in Create User endpoint

webui/static/hoover/websocket.js

@@ -62,6 +62,8 @@ function _wsConnect() {
                 setTimeout(_wsConnect, 100);
             }).catch(() => {
                 _wsRefreshing = false;
+                _wsReconnectMs = Math.min(_wsReconnectMs * 2 + 1000, 15000);
+                setTimeout(_wsConnect, _wsReconnectMs);
             });
             return;
         }