Fix gt shutdown to stop daemon (fixes #299)

gt shutdown was not stopping the daemon, which caused it to restart
agents (witnesses, refineries) after shutdown completed. The daemon
heartbeats every 3 minutes and calls ensureWitnessesRunning() and
ensureRefineriesRunning(), which would notice the sessions were dead
and restart them.

This adds daemon stop logic to both runGracefulShutdown (as Phase 6)
and runImmediateShutdown (after polecat cleanup), matching the behavior
that gt down already has.

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

internal/cmd/start.go

@@ -13,6 +13,7 @@ import (
 	"github.com/steveyegge/gastown/internal/config"
 	"github.com/steveyegge/gastown/internal/constants"
 	"github.com/steveyegge/gastown/internal/crew"
+	"github.com/steveyegge/gastown/internal/daemon"
 	"github.com/steveyegge/gastown/internal/deacon"
 	"github.com/steveyegge/gastown/internal/git"
 	"github.com/steveyegge/gastown/internal/mayor"
@@ -465,6 +466,12 @@ func runGracefulShutdown(t *tmux.Tmux, gtSessions []string, townRoot string) err
 		cleanupPolecats(townRoot)
 	}
 
+	// Phase 6: Stop the daemon
+	fmt.Printf("\nPhase 6: Stopping daemon...\n")
+	if townRoot != "" {
+		stopDaemonIfRunning(townRoot)
+	}
+
 	fmt.Println()
 	fmt.Printf("%s Graceful shutdown complete (%d sessions stopped)\n", style.Bold.Render("✓"), stopped)
 	return nil
@@ -484,6 +491,13 @@ func runImmediateShutdown(t *tmux.Tmux, gtSessions []string, townRoot string) er
 		cleanupPolecats(townRoot)
 	}
 
+	// Stop the daemon
+	if townRoot != "" {
+		fmt.Println()
+		fmt.Println("Stopping daemon...")
+		stopDaemonIfRunning(townRoot)
+	}
+
 	fmt.Println()
 	fmt.Printf("%s Gas Town shutdown complete (%d sessions stopped)\n", style.Bold.Render("✓"), stopped)
 
@@ -633,6 +647,21 @@ func cleanupPolecats(townRoot string) {
 	}
 }
 
+// stopDaemonIfRunning stops the daemon if it is running.
+// This prevents the daemon from restarting agents after shutdown.
+func stopDaemonIfRunning(townRoot string) {
+	running, _, _ := daemon.IsRunning(townRoot)
+	if running {
+		if err := daemon.StopDaemon(townRoot); err != nil {
+			fmt.Printf("  %s Daemon: %s\n", style.Dim.Render("○"), err.Error())
+		} else {
+			fmt.Printf("  %s Daemon stopped\n", style.Bold.Render("✓"))
+		}
+	} else {
+		fmt.Printf("  %s Daemon not running\n", style.Dim.Render("○"))
+	}
+}
+
 // runStartCrew starts a crew workspace, creating it if it doesn't exist.
 // This combines the functionality of 'gt crew add' and 'gt crew at --detached'.
 func runStartCrew(cmd *cobra.Command, args []string) error {