5c39662cc2
A gtkmm-4.0 control panel (behind -Dgui=true, default off): refresh shows discovered receivers (grouped and preference-sorted), a bitrate scale, and start/stop that runs the whole session on a worker thread so the interactive portal picker never blocks the UI. The CLI and the GUI now share the new sc_app_core static library holding the pipelines, session orchestration (negotiation + PLI feedback), and a state store. The sender pipeline publishes its state to $XDG_RUNTIME_DIR/screencast/sender.json (session id, receiver, bitrate, pid, start time; stale files detected by pid liveness) and persists the last session for one-click restarts. The new 'screencast waybar' subcommand prints a waybar module line and its --toggle flag stops a running sender gracefully or spawns a detached restart of the last receiver. Waybar on the dev machine is wired: custom/screencast module with click-to-toggle and right-click panel, plus styles, with a timestamped backup of both config files. Both binaries are installed to /usr/local/bin. Validated: waybar output (idle and streaming states with a synthetic state file), GUI launches on the desktop (window observed via hyprctl), meson test 5/5 in both build configurations, formatting clean.