When a scanner is shown a QR code of a different kind than it expects, it
now tells the user what they actually scanned and where to use it, instead
of a generic "invalid" message.
Link recognition is done in the core: a new chat_check_link export
classifies a scanned string using the same decoders the views use to
process the links (connection link, server address, migration file link,
desktop address, security code), returning a typed result. Each scanner
calls checkLink first; the expected type proceeds to that scanner's normal
success path, a recognised-but-wrong type shows a shared wrong-type alert
saying what it is and where to use it, and an unrecognised string falls
back to that scanner's own contextual error. Mirrored on Android, desktop
and iOS.
Note: the iOS Swift was written without an Xcode toolchain and is not yet
compiled — needs a Mac/CI build to verify.
* desktop: pick a free port for the call server if 50395 is in use
startServer() bound a hard-coded port (50395); when it was already in use,
NanoWSD threw "BindException: Address already in use: bind" and the call
failed. It now falls back to an OS-assigned free port, and WebRTCController
opens the browser at the actually-bound port (server.listeningPort) -- still
50395 in the normal case, so browser camera/mic permission stays put.
* plans: justify call server port-bind fix
Narasimha-sc