Unified the two overlapping role detection structs:
- RoleContext (prime.go) is now a type alias for RoleInfo
- detectRole() now returns RoleInfo directly
- Added WorkDir field to RoleInfo
- GetRoleWithContext now populates WorkDir
This eliminates code duplication between prime.go and role.go while
maintaining backward compatibility through the type alias.
- New gt role subcommands: show, home, detect, list, env
- Role detection now checks GT_ROLE env var first, falls back to cwd
- gt prime shows warning when role/cwd mismatch detected
- gt mol status uses env-aware role detection
- gt handoff injects GT_ROLE and resets to role canonical home
- Fixed witness/refinery home paths (was missing /rig suffix)
This prevents role confusion when agents wander to wrong directories.
After handoff, agents are always restored to their canonical home.
