Add ACMCC app source, Supabase backend, and project config

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

supabase/migrations/20260326034022_de41ddfb-dcf4-462e-b5e7-24e2f6f5a9a6.sql

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+
+ALTER TABLE public.announcements ADD COLUMN IF NOT EXISTS association_id uuid REFERENCES public.associations(id);
+
+-- Allow anonymous users to read public announcements
+CREATE POLICY "Anyone can read public announcements"
+  ON public.announcements FOR SELECT
+  TO anon
+  USING (visibility = 'public' AND status = 'active');