feat: 3-tier role system across all platform apps

Portal:
- Replace is_admin boolean with role column (admin/advanced/standard)
- Settings UI: 3-tier portal role select + per-app role dropdowns
- /portal-return endpoint: re-establishes session from JWT for sub-app back-links
- /api/internal/nv-users: internal endpoint for NetworkView user sync
- portal/migrate_roles.py: one-time DB migration script
- Role badges (admin/advanced/standard) in topbar and settings table

DigiServer:
- Add editor and viewer roles (portal advanced->editor, standard->viewer)
- PlaylistPermission model: grant viewer users edit access to specific playlists
- app/utils/access.py: shared editor_required, admin_required, can_edit_playlist helpers
- Content routes: editor_required on create/delete, per-playlist permission check on mutations
- Admin: playlist_permissions route + template to manage viewer playlist grants
- Base template: hide Admin nav for viewers, Portal button (⬡) returns to portal
- content_list_new: hide create/delete for viewers; Manage vs View button per permission
- manage_playlist_content: view-only mode when user lacks edit permission

NetworkView:
- backend/src/middleware/rbac.js: requireRole + requireWriteAccess helpers
- site_permissions table: one site per advanced user
- All mutating routes guarded (admin=all, advanced=assigned site, viewer=read-only)
- Portal SSO auto-upsert: user row synced from X-Auth-Role on every request
- GET /api/users: merges portal users list with local NV data (all 4 portal users visible)
- GET/PUT /api/users/:id/site-permission: assign site to advanced user
- Settings Users tab: role badges, site dropdown for advanced, (portal only) indicator
- Sidebar: ⬡ Portal button between Settings and Logout
- Frontend build: VITE_API_BASE=/networkview/api now set in start-dev.sh

IT Assets / Server Monitor:
- portal_sso.py updated: map advanced->editor/viewer, standard->readonly
- AdminUser model: add editor role + is_editor property

Server_Monitorizare_v2/app/utils/portal_sso.py

@@ -3,7 +3,12 @@ Portal SSO middleware for Server Monitor.
 
 When the umbrella nginx verifies the portal JWT it sets two headers:
   X-Auth-Username  — the portal username
-  X-Auth-Role      — 'admin' or 'user'
+  X-Auth-Role      — 'admin' | 'advanced' | 'standard'
+
+Portal role → Server Monitor access level:
+  admin    — full access: view all, run Ansible, manage config
+  advanced — can view all data and trigger safe operations
+  standard — read-only dashboard view
 
 This before_request handler stores them in Flask's g so templates
 and routes can access the current user without a local user DB.
@@ -17,11 +22,16 @@ def init_portal_sso(app):
     @app.before_request
     def _portal_sso():
         g.portal_user = request.headers.get('X-Auth-Username', '').strip() or None
-        g.portal_role = request.headers.get('X-Auth-Role', 'user').strip()
+        raw_role = request.headers.get('X-Auth-Role', 'standard').strip()
+        # Normalise to the three known tiers; unknown values fall back to 'standard'
+        g.portal_role = raw_role if raw_role in ('admin', 'advanced', 'standard') else 'standard'
 
     @app.context_processor
     def _inject_portal_user():
         return {
             'portal_user': getattr(g, 'portal_user', None),
-            'portal_role': getattr(g, 'portal_role', 'user'),
+            'portal_role': getattr(g, 'portal_role', 'standard'),
+            # Convenience booleans available in all templates
+            'portal_is_admin':    getattr(g, 'portal_role', 'standard') == 'admin',
+            'portal_is_advanced': getattr(g, 'portal_role', 'standard') in ('admin', 'advanced'),
         }