refactor: flatten monorepo structure to backend/ frontend/ devops/

Rename subdirectories for a cleaner single-repo layout:
- website-monitoring-backend/  → backend/
- website-monitoring-frontend/ → frontend/
- website-monitoring-devops/   → devops/

Update all references in package.json scripts, CI workflows,
docker-compose, pre-commit hooks, and documentation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/supabase/migrations/20250813102540_fix_user_select_rls.sql

@@ -0,0 +1,21 @@
+-- Fix RLS policies for users table to allow proper user details loading
+-- Add policies for SELECT operations on users table
+
+-- Allow users to select their own profile
+CREATE POLICY "Users can select their own profile" ON public.users
+FOR SELECT USING (auth.uid() = id);
+
+-- Allow users to select profiles in their organization
+CREATE POLICY "Users can select profiles in their organization" ON public.users
+FOR SELECT USING (
+  organization_id IN (
+    SELECT organization_id FROM public.users WHERE id = auth.uid()
+  )
+);
+
+-- Allow service role to select any user (for admin operations)
+CREATE POLICY "Service role can select any user" ON public.users
+FOR SELECT USING (auth.role() = 'service_role');
+
+-- Refresh schema cache
+NOTIFY pgrst, 'reload schema';