feat(ux): F1 toggles help, --user flag, connect.sh fresh-build

- app.rs: F1 now closes the help overlay (toggle), not just opens it
- host-house.sh: add --user/--name flag to override the $USER default seat
- connect.sh: incremental cargo build before launch so the UI is never a
  stale release binary; --no-build escape hatch for toolchain-less joiners

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hh/src/app.rs

@@ -1014,8 +1014,9 @@ pub async fn run(params: net::ConnParams, mut session: Session, mut theme: Theme
                                 KeyCode::PageDown => app.help_scroll = (app.help_scroll + 10).min(max),
                                 KeyCode::Home => app.help_scroll = 0,
                                 KeyCode::End => app.help_scroll = max,
-                                KeyCode::Esc => {
-                                    app.show_help = false; // Esc dismisses the overlay
+                                KeyCode::Esc | KeyCode::F(1) => {
+                                    // Esc dismisses; F1 toggles the overlay back shut
+                                    app.show_help = false;
                                     app.help_scroll = 0;
                                 }
                                 _ => {} // ignore other keys so the menu stays put