Add test coverage for class instance scope survival in conditional/loop blocks

[Copilot]

Addresses review feedback requesting test coverage for class instances created in inner scopes (se/enquanto) and assigned to outer-scope variables. This scenario is critical with ReferenciaMontao implementation, where incorrect deallocation on scope exit could invalidate valid references.

Tests Added

• se block scope test: Verifies instance created inside conditional remains accessible after block exit
• enquanto loop scope test: Verifies instance created inside loop remains accessible after iteration completes

Both tests confirm instance properties remain valid and accessible from the outer scope variable.

classe Produto {
  nome: texto
  preco: numero
  construtor(nome, preco) {
    isto.nome = nome
    isto.preco = preco
  }
}
var produto
se (verdadeiro) {
  produto = Produto("Notebook", 2500)
}
escreva(produto.nome)    // Should output: Notebook
escreva(produto.preco)   // Should output: 2500

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[leonelsanchesdasilva]

@copilot Please rebase with principal.