chore: remove the qbzd crate from the workspace

qbzd (the dormant TUI crate) pinned ratatui -> unicode-width =0.2.0,
which blocked upgrading Slint past 1.14. Dropped from the workspace
members; the directory stays on disk, just no longer built.

cc

crates/Cargo.toml

@@ -18,7 +18,6 @@ members = [
     "qconnect-protocol",
     "qconnect-transport-ws",
     "qconnect-app",
-    "qbzd",
     "qbz-slint",
     "qbz-credentials",
 ]