feat: Add rig infra cycling (witness ↔ refinery)

Extended the unified cycle system to include rig infrastructure sessions:
- Witness ↔ Refinery (per rig) now cycle with C-b n/p

Also moved SetCycleBindings into ConfigureGasTownSession so ALL Gas Town
sessions automatically get the unified cycle bindings. Removed redundant
individual calls from crew, mayor, and deacon startup code.

Cycle groups are now:
- Town: Mayor ↔ Deacon
- Crew (per rig): All crew members in same rig
- Infra (per rig): Witness ↔ Refinery

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

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

internal/tmux/tmux.go

@@ -611,6 +611,9 @@ func (t *Tmux) ConfigureGasTownSession(session string, theme Theme, rig, worker,
 	if err := t.SetFeedBinding(session); err != nil {
 		return fmt.Errorf("setting feed binding: %w", err)
 	}
+	if err := t.SetCycleBindings(session); err != nil {
+		return fmt.Errorf("setting cycle bindings: %w", err)
+	}
 	return nil
 }