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/cmd/cycle.go

@@ -1,6 +1,9 @@
 package cmd
 
 import (
+	"fmt"
+	"os/exec"
+	"sort"
 	"strings"
 
 	"github.com/spf13/cobra"
@@ -28,6 +31,7 @@ var cycleCmd = &cobra.Command{
 Session groups:
 - Town sessions: Mayor ↔ Deacon
 - Crew sessions: All crew members in the same rig (e.g., gastown/crew/max ↔ gastown/crew/joe)
+- Rig infra sessions: Witness ↔ Refinery (per rig)
 
 The appropriate cycling is detected automatically from the session name.`,
 }
@@ -83,6 +87,89 @@ func cycleToSession(direction int, sessionOverride string) error {
 		return cycleCrewSession(direction, session)
 	}
 
-	// Unknown session type (polecat, witness, refinery) - do nothing
+	// Check if it's a rig infra session (witness or refinery)
+	if rig := parseRigInfraSession(session); rig != "" {
+		return cycleRigInfraSession(direction, session, rig)
+	}
+
+	// Unknown session type (polecat) - do nothing
 	return nil
 }
+
+// parseRigInfraSession extracts rig name if this is a witness or refinery session.
+// Returns empty string if not a rig infra session.
+// Format: gt-<rig>-witness or gt-<rig>-refinery
+func parseRigInfraSession(session string) string {
+	if !strings.HasPrefix(session, "gt-") {
+		return ""
+	}
+	rest := session[3:] // Remove "gt-" prefix
+
+	// Check for -witness or -refinery suffix
+	if strings.HasSuffix(rest, "-witness") {
+		return strings.TrimSuffix(rest, "-witness")
+	}
+	if strings.HasSuffix(rest, "-refinery") {
+		return strings.TrimSuffix(rest, "-refinery")
+	}
+	return ""
+}
+
+// cycleRigInfraSession cycles between witness and refinery sessions for a rig.
+func cycleRigInfraSession(direction int, currentSession, rig string) error {
+	// Find running infra sessions for this rig
+	witnessSession := fmt.Sprintf("gt-%s-witness", rig)
+	refinerySession := fmt.Sprintf("gt-%s-refinery", rig)
+
+	var sessions []string
+	allSessions, err := listTmuxSessions()
+	if err != nil {
+		return err
+	}
+
+	for _, s := range allSessions {
+		if s == witnessSession || s == refinerySession {
+			sessions = append(sessions, s)
+		}
+	}
+
+	if len(sessions) == 0 {
+		return nil // No infra sessions running
+	}
+
+	// Sort for consistent ordering
+	sort.Strings(sessions)
+
+	// Find current position
+	currentIdx := -1
+	for i, s := range sessions {
+		if s == currentSession {
+			currentIdx = i
+			break
+		}
+	}
+
+	if currentIdx == -1 {
+		return nil // Current session not in list
+	}
+
+	// Calculate target index (with wrapping)
+	targetIdx := (currentIdx + direction + len(sessions)) % len(sessions)
+
+	if targetIdx == currentIdx {
+		return nil // Only one session
+	}
+
+	// Switch to target session
+	cmd := exec.Command("tmux", "switch-client", "-t", sessions[targetIdx])
+	return cmd.Run()
+}
+
+// listTmuxSessions returns all tmux session names.
+func listTmuxSessions() ([]string, error) {
+	out, err := exec.Command("tmux", "list-sessions", "-F", "#{session_name}").Output()
+	if err != nil {
+		return nil, err
+	}
+	return splitLines(string(out)), nil
+}