feat: scaffold supabase multi-tenant backend

supabase/seed.sql

@@ -0,0 +1,47 @@
+insert into public.tenants (id, slug, name, status, mode)
+values (
+  '00000000-0000-0000-0000-000000000001',
+  'master',
+  '升本刷题通主租户',
+  'active',
+  'platform_owned'
+)
+on conflict (id) do nothing;
+
+insert into public.tenant_domains (tenant_id, host, domain_type, status, is_primary)
+values (
+  '00000000-0000-0000-0000-000000000001',
+  'localhost',
+  'system',
+  'active',
+  true
+)
+on conflict (host) do nothing;
+
+insert into public.tenant_branding (tenant_id, brand_name, short_name, slogan)
+values (
+  '00000000-0000-0000-0000-000000000001',
+  '升本刷题通',
+  '刷题通',
+  '多租户专升本题库 SaaS'
+)
+on conflict (tenant_id) do nothing;
+
+insert into public.tenant_settings (tenant_id, feature_flags, admin_feature_flags, public_config)
+values (
+  '00000000-0000-0000-0000-000000000001',
+  '{"enableStore":true,"enableLeaderboard":true,"enableVocabulary":true,"enableHandbook":true,"enableScoreline":true}'::jsonb,
+  '{"enableTenantManagement":true,"enableQuestionCRUD":true,"enableRevenueLedger":true,"enableMarketing":true}'::jsonb,
+  '{"examDate":"","appUrl":"http://127.0.0.1:5173"}'::jsonb
+)
+on conflict (tenant_id) do nothing;
+
+insert into public.tenant_auth_providers (tenant_id, provider, status, display_name, config_public)
+values (
+  '00000000-0000-0000-0000-000000000001',
+  'mock',
+  'testing',
+  '本地模拟短信',
+  '{"channel":"local-dev"}'::jsonb
+)
+on conflict (tenant_id, provider) do nothing;