feat(01-02): add seed file for development verification

- Verify plans exist before seeding
- Log seed completion with NOTICE
- Minimal seed - plans created in migration, profiles via trigger

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

supabase/seed.sql

@@ -0,0 +1,20 @@
+-- Seed file for development
+-- Note: Plans are already seeded in migration
+-- This file is for additional test data if needed
+--
+-- Phase: 01-foundation-auth, Plan: 02
+-- Created: 2026-01-31
+
+-- Verify plans exist
+DO $$
+BEGIN
+  IF NOT EXISTS (SELECT 1 FROM public.plans WHERE name = 'free') THEN
+    RAISE EXCEPTION 'Plans not found - run migration first';
+  END IF;
+END $$;
+
+-- Log seed completion
+DO $$
+BEGIN
+  RAISE NOTICE 'Seed completed. Plans available: free, creator, pro';
+END $$;