feat: expand manageableSlugs to include entire tenant tree for users

Allows users and tenant admins to view users across all tenants within their hierarchy (both parent and child organizations) instead of just their direct tenant.

backend/internal/handler/user_handler.go

@@ -103,13 +103,16 @@ func (h *UserHandler) ListUsers(c *fiber.Ctx) error {
 	if requesterRole == domain.RoleTenantAdmin || requesterRole == domain.RoleUser || requesterRole == domain.RoleRPAdmin {
 		profile, _ := c.Locals("user_profile").(*domain.UserProfileResponse)
 		if profile != nil {
+			var baseTenantIDs []string
 			for _, t := range profile.ManageableTenants {
 				manageableSlugs[strings.ToLower(t.Slug)] = true
-				manageableSlugs[strings.ToLower(t.ID)] = true // Add ID as well
+				manageableSlugs[strings.ToLower(t.ID)] = true
+				baseTenantIDs = append(baseTenantIDs, t.ID)
 			}
 			for _, t := range profile.JoinedTenants {
 				manageableSlugs[strings.ToLower(t.Slug)] = true
 				manageableSlugs[strings.ToLower(t.ID)] = true
+				baseTenantIDs = append(baseTenantIDs, t.ID)
 			}
 			// Include primary tenant slug if not already there
 			if profile.CompanyCode != "" {
@@ -117,6 +120,47 @@ func (h *UserHandler) ListUsers(c *fiber.Ctx) error {
 			}
 			if profile.TenantID != nil {
 				manageableSlugs[strings.ToLower(*profile.TenantID)] = true
+				baseTenantIDs = append(baseTenantIDs, *profile.TenantID)
+			}
+
+			// Expand manageableSlugs to the entire tenant tree (root + all descendants)
+			if h.TenantService != nil && len(baseTenantIDs) > 0 {
+				allTenants, _, err := h.TenantService.ListTenants(c.Context(), 10000, 0, "")
+				if err == nil {
+					parentMap := make(map[string]string)
+					for _, t := range allTenants {
+						if t.ParentID != nil {
+							parentMap[t.ID] = *t.ParentID
+						}
+					}
+					
+					// Function to find the root of any given tenant
+					findRoot := func(id string) string {
+						curr := id
+						for {
+							p, exists := parentMap[curr]
+							if !exists || p == "" {
+								break
+							}
+							curr = p
+						}
+						return curr
+					}
+
+					// Collect root IDs for all base tenants
+					roots := make(map[string]bool)
+					for _, id := range baseTenantIDs {
+						roots[findRoot(id)] = true
+					}
+
+					// If a tenant shares a root with any base tenant, it's in the same tree family
+					for _, t := range allTenants {
+						if roots[findRoot(t.ID)] {
+							manageableSlugs[strings.ToLower(t.Slug)] = true
+							manageableSlugs[strings.ToLower(t.ID)] = true
+						}
+					}
+				}
 			}
 		}
 	}