feat: Set and Forget - Seamless Gas Town Integration (#255)

Adds shell integration for automatic Gas Town context detection.

Features:
- `gt enable` / `gt disable` - Global on/off switch
- `gt shell install|remove|status` - Shell integration management
- `gt rig quick-add [path]` - One-command project setup
- `gt uninstall` - Clean removal with options
- Shell hook auto-sets GT_TOWN_ROOT/GT_RIG on cd

Implementation:
- XDG-compliant state storage (~/.local/state/gastown/)
- Safe RC file manipulation with block markers
- Environment overrides (GASTOWN_DISABLED/ENABLED)
- Doctor check for global state validation

Co-authored-by: Sohail Mohammad <sohailm25@gmail.com>

internal/rig/manager.go

@@ -614,6 +614,11 @@ func (m *Manager) initBeads(rigPath, prefix string) error {
 		fmt.Printf("   ⚠ Could not add route to town beads: %v\n", err)
 	}
 
+	typesCmd := exec.Command("bd", "config", "set", "types.custom", "agent,role,rig,convoy,slot")
+	typesCmd.Dir = rigPath
+	typesCmd.Env = filteredEnv
+	_, _ = typesCmd.CombinedOutput()
+
 	return nil
 }