fix: ensure all manageable tenants are visible for tenant admin and refine overview UI

backend/internal/handler/auth_handler.go

@@ -4046,6 +4046,14 @@ func (h *AuthHandler) resolveCurrentProfile(c *fiber.Ctx) (*domain.UserProfileRe
 		}
 	}
 
+	// [New] Fetch manageable tenants for Tenant Admin
+	if profile.Role == domain.RoleTenantAdmin && h.TenantService != nil {
+		manageable, err := h.TenantService.ListManageableTenants(c.Context(), profile.ID)
+		if err == nil {
+			profile.ManageableTenants = manageable
+		}
+	}
+
 	// 4. Save to Redis Cache (Short TTL)
 	// IMPORTANT: In dev mode, if role was overridden, we should NOT cache it under the token key
 	// or we should include the mock role in the cache key.