deadlock, and OFFER/encode resolution mismatch
Found live-testing on real hardware after the first round of fixes:
1. mDNS resolves one Chromecast on every local address it has (a private
IPv4 and a link-local IPv6 in the common case), as separate
CastDeviceFound events for the same id. The device map was a plain
HashMap::insert, so whichever address resolved last won -- and a bare
fe80:: address has no interface scope attached, so connecting to it
fails outright. This is what "failed to connect and launch the
Mirroring receiver" actually was; the message just didn't say why,
since daemon.rs was converting the anyhow::Error with to_string()
(Display, outermost .context() only) instead of "{e:#}" (full chain).
Fixed both: prefer an already-usable host over a link-local one
instead of always taking the newest resolution, and preserve the full
error chain to the GUI/bread event log.
2. The CASTV2 receive loop (run_io_loop) treated any error from
device.receive() as connection-fatal and ended the whole loop --
including a plain JSON deserialization failure on a single
MEDIA_STATUS message (rust_cast's struct requires an `images` field
this receiver didn't send). That killed the receiver-status/control
channel for the rest of every session, on the very first status
update, while the RTP stream itself kept flowing obliviously.
rust_cast::Error already distinguishes Io/Tls/Dns (actually fatal)
from Serialization/Parsing/etc (a bad message, not a dead socket) --
only end the loop on the former now.
3. CastSession::stop() blocks on an unbounded reply_rx.recv() waiting for
the io thread's device.receiver.stop_app() -- a network round trip
rust_cast gives no way to put a read timeout on. If the receiver ever
stops responding, that never returns, and since the daemon actor
processes one command at a time, a single wedged stop_cast freezes
every future IPC request too, recoverable only by killing the process
-- which is exactly what was observed live. Bounded both that wait and
join_pump's thread joins to 5s; past that, log a warning and tear down
anyway rather than hang forever. The abandoned thread(s) may leak, but
a leak beats an unrecoverable daemon.
4. VideoParams::default() advertised 1920x1080 in the OFFER while
build_video_pipeline_for_streaming actually encodes 1280x720 --
negotiated and actual resolution disagreeing is a real protocol
violation, not just soft video, and a plausible cause of a receiver
decoder corrupting or freezing outright rather than merely looking
worse. Made the OFFER match what's actually sent.