fix: prevent tmux link-window from auto-switching windows (gt-wmhj)

When running `gt crew at <other>` from inside tmux, the linked window
would auto-select, causing users to unknowingly switch agents. Add -d
flag to keep user in their current window.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/tmux/tmux.go

@@ -532,9 +532,10 @@ func (t *Tmux) ConfigureGasTownSession(session string, theme Theme, rig, worker,
 // LinkWindow links a window from another session into the current session.
 // This allows viewing another session's window as a tab without switching sessions.
 // Useful when already inside tmux and want to see another session.
+// Uses -d flag to NOT auto-select the new window, keeping user in current window.
 func (t *Tmux) LinkWindow(sourceSession string, windowIndex int) error {
 	source := fmt.Sprintf("%s:%d", sourceSession, windowIndex)
-	_, err := t.run("link-window", "-s", source)
+	_, err := t.run("link-window", "-s", source, "-d")
 	return err
 }