fix: code review fixes from gt-2tp and gt-y0t

- Replace custom contains() with strings.Contains in init.go
- Make session stop --force flag actually work
- Update session.Manager.Stop() to accept force parameter

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

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

internal/session/manager.go

@@ -134,7 +134,8 @@ func (m *Manager) Start(polecat string, opts StartOptions) error {
 }
 
 // Stop terminates a polecat session.
-func (m *Manager) Stop(polecat string) error {
+// If force is true, skips graceful shutdown and kills immediately.
+func (m *Manager) Stop(polecat string, force bool) error {
 	sessionID := m.sessionName(polecat)
 
 	// Check if session exists
@@ -146,9 +147,11 @@ func (m *Manager) Stop(polecat string) error {
 		return ErrSessionNotFound
 	}
 
-	// Try graceful shutdown first
-	m.tmux.SendKeysRaw(sessionID, "C-c") // Ctrl+C
-	time.Sleep(100 * time.Millisecond)
+	// Try graceful shutdown first (unless forced)
+	if !force {
+		m.tmux.SendKeysRaw(sessionID, "C-c") // Ctrl+C
+		time.Sleep(100 * time.Millisecond)
+	}
 
 	// Kill the session
 	if err := m.tmux.KillSession(sessionID); err != nil {
@@ -237,7 +240,7 @@ func (m *Manager) Inject(polecat, message string) error {
 }
 
 // StopAll terminates all sessions for this rig.
-func (m *Manager) StopAll() error {
+func (m *Manager) StopAll(force bool) error {
 	infos, err := m.List()
 	if err != nil {
 		return err
@@ -245,7 +248,7 @@ func (m *Manager) StopAll() error {
 
 	var lastErr error
 	for _, info := range infos {
-		if err := m.Stop(info.Polecat); err != nil {
+		if err := m.Stop(info.Polecat, force); err != nil {
 			lastErr = err
 		}
 	}

internal/session/manager_test.go

@@ -105,7 +105,7 @@ func TestStopNotFound(t *testing.T) {
 	}
 	m := NewManager(tmux.NewTmux(), r)
 
-	err := m.Stop("Toast")
+	err := m.Stop("Toast", false)
 	if err != ErrSessionNotFound {
 		t.Errorf("Stop = %v, want ErrSessionNotFound", err)
 	}