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/20250813102535_fix_user_rls_final.sql

@@ -0,0 +1,24 @@
+-- Final fix for user RLS policies
+-- Drop the conflicting policies and create the correct ones
+
+-- Drop existing conflicting policies
+DROP POLICY IF EXISTS "Allow user insert for anon" ON "public"."users";
+DROP POLICY IF EXISTS "Allow user insert for authenticated" ON "public"."users";
+DROP POLICY IF EXISTS "Allow user insert for authenticator" ON "public"."users";
+DROP POLICY IF EXISTS "Allow user insert for dashboard_user" ON "public"."users";
+
+-- Create the correct policies
+DROP POLICY IF EXISTS "Allow user profile creation during registration" ON "public"."users";
+CREATE POLICY "Allow user profile creation during registration" ON "public"."users" 
+FOR INSERT TO "anon" WITH CHECK (true);
+
+DROP POLICY IF EXISTS "Allow authenticated user profile creation" ON "public"."users";
+CREATE POLICY "Allow authenticated user profile creation" ON "public"."users" 
+FOR INSERT TO "authenticated" WITH CHECK (auth.uid() = id);
+
+DROP POLICY IF EXISTS "Allow user profile creation for service role" ON "public"."users";
+CREATE POLICY "Allow user profile creation for service role" ON "public"."users" 
+FOR INSERT TO "service_role" WITH CHECK (true);
+
+-- Refresh schema cache
+NOTIFY pgrst, 'reload schema';