Lock the right pane while focused, add project focus, quiet lead

internal/agents/manager.go

@@ -53,6 +53,7 @@ type Manager struct {
 	rateLimits   map[api.AgentSessionVendor]map[string]any
 	merges       map[string]string
 	leadAnswered map[string]bool
+	paneFocused  map[string]bool
 
 	deliverMu sync.Mutex
 	capMu     sync.Mutex
@@ -100,6 +101,7 @@ func New(st *store.Store, limits Limits, worktreeRoot, leadRoot string) *Manager
 		rateLimits:   map[api.AgentSessionVendor]map[string]any{},
 		merges:       map[string]string{},
 		leadAnswered: map[string]bool{},
+		paneFocused:  map[string]bool{},
 		signals:      make(chan api.Event, 1024),
 		snaps:        map[string]*snapState{},
 		bad:          newBadLines(),