feat: migrate to docker-compose with selfhosted-supabase-mcp

- Replace legacy directory structure (api/, db/, functions/, logs/, pooler/) with
  single docker-compose.yml based self-hosted setup
- Add selfhosted-supabase-mcp TypeScript MCP server for database management
- Add .dockerignore for Docker build context
- Update .gitignore to exclude .env files, volumes/, backups, logs

selfhosted-supabase-mcp/src/__tests__/setup.ts

@@ -0,0 +1,8 @@
+/**
+ * Test setup file for Bun test runner.
+ * This file is preloaded before all tests run.
+ */
+
+// Global test setup - mock environment variables
+process.env.SUPABASE_URL = 'http://localhost:54321';
+process.env.SUPABASE_ANON_KEY = 'test-anon-key';