chore(deps): bump mdns-sd from 0.11.5 to 0.19.1 in /src-tauri

Bumped only for src-tauri's qconnect-discovery path. qbz-cast (chromecast/
DLNA) stays on 0.11 because mdns-sd 0.19 changed the address API
(HashSet<IpAddr> → HashSet<ScopedIp>) and adapting qbz-cast is real
work outside dependabot scope. Workspace now carries both versions
in the graph; both compile and operate independently.

cc

src-tauri/Cargo.toml

@@ -36,7 +36,7 @@ qbz-library = { path = "../crates/qbz-library" }
 qbz-cast = { path = "../crates/qbz-cast" }
 qbz-cmaf = { path = "../crates/qbz-cmaf" }
 qbz-secrets = { path = "../crates/qbz-secrets" }
-mdns-sd = "0.11"
+mdns-sd = "0.19"
 qconnect-app = { path = "../crates/qconnect-app" }
 qconnect-core = { path = "../crates/qconnect-core" }
 qconnect-transport-ws = { path = "../crates/qconnect-transport-ws" }