fix: restore agent override support lost in manager refactors

The manager refactors (ea8bef2, 72544cc0) conflicted with the agent
override feature, causing regressions:

Deacon (ea8bef2):
- Lost agentOverride parameter
- Re-added respawn loop (removed in 5f2e16f)
- Lost GUPP (startup + propulsion nudges)

Crew (72544cc0):
- Lost agentOverride wiring to StartOptions
- --agent flag had no effect on crew refresh/restart

This fix restores agent override support and GUPP while keeping
improvements from the manager refactors (zombie detection, etc).

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

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

internal/cmd/start.go

@@ -203,7 +203,7 @@ func startCoreAgents(townRoot string, agentOverride string) error {
 
 	// Start Deacon (health monitor)
 	deaconMgr := deacon.NewManager(townRoot)
-	if err := deaconMgr.Start(); err != nil {
+	if err := deaconMgr.Start(agentOverride); err != nil {
 		if err == deacon.ErrAlreadyRunning {
 			fmt.Printf("  %s Deacon already running\n", style.Dim.Render("○"))
 		} else {
@@ -694,6 +694,7 @@ func runStartCrew(cmd *cobra.Command, args []string) error {
 	err = crewMgr.Start(name, crew.StartOptions{
 		Account:         startCrewAccount,
 		ClaudeConfigDir: claudeConfigDir,
+		AgentOverride:   startCrewAgentOverride,
 	})
 	if err != nil {
 		if errors.Is(err, crew.ErrSessionRunning) {