fix: ensure Wi-Fi is up before the browser calls the API

fix: ensure Wi-Fi is up before the browser calls the API The browser views went straight to the API with no connectivity check, while the older save-link path already guarded with NetworkMgr:isOnline(). KOReader turns Wi-Fi off aggressively, so on a real device the first browse attempt failed at the socket layer and surfaced as the opaque 'Network error occurred' - with no HTTP status in the log, which sent me hunting a TLS problem that did not exist. Browser:navigate() now routes through NetworkMgr:beforeWifiAction() for any view that talks to the API, re-running the navigation once the connection is up. The static root view is exempt so opening the browser does not prompt for Wi-Fi. Diagnosed on a Kindle PW4: TLS was fine (TLS 1.2 negotiated, ISRG Root X1/X2 both present in KOReader's ca-bundle), the URL was correct, and the same endpoint worked from a laptop.