feat(types): add rig identity bead type (gt-zmznh)

- Add TypeRig constant to IssueType enum
- Update IsValid() method to include TypeRig
- Add UI color (orange) and style for rig type
- Update CLI flag descriptions in create and update commands
- Add Obsidian export tag for rig type
- Add comprehensive test cases for rig and other newer types

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

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

cmd/bd/export_obsidian.go

@@ -45,6 +45,7 @@ var obsidianTypeTag = map[types.IssueType]string{
 	types.TypeGate:         "#Gate",
 	types.TypeAgent:        "#Agent",
 	types.TypeRole:         "#Role",
+	types.TypeRig:          "#Rig",
 	types.TypeConvoy:       "#Convoy",
 	types.TypeEvent:        "#Event",
 }