fix: Remove hardcoded actors, let bd use default chain

bd defaults to $BD_ACTOR → git config user.name → $USER, which is
more accurate for system tools like doctor and rig init.

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

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

internal/doctor/patrol_check.go

@@ -118,7 +118,6 @@ func (c *PatrolMoleculesExistCheck) Fix(ctx *CheckContext) error {
 				"--title="+mol,
 				"--description="+desc,
 				"--priority=2",
-				"--actor=gt-doctor",
 			)
 			cmd.Dir = rigPath
 			if err := cmd.Run(); err != nil {

internal/rig/manager.go

@@ -534,7 +534,6 @@ func (m *Manager) seedPatrolMoleculesManually(rigPath string) error {
 			"--title="+mol.title,
 			"--description="+mol.desc,
 			"--priority=2",
-			"--actor=gt-rig-init",
 		)
 		cmd.Dir = rigPath
 		if err := cmd.Run(); err != nil {