fix(webmail): a lista de destinos deixava de fora as pastas do utilizador

Encontrado a validar na produção, depois do deploy: o selector de pasta
de destino na tela de regras mostrava apenas INBOX, Archive, Junk e
Trash - exactamente sem as pastas que o utilizador tinha criado, que
são aquelas para que uma regra de arquivo costuma ser escrita.

A tela de regras escolhe um destino sem nenhuma mensagem aberta, por
isso não tem "pasta actual" para excluir e passava uma string vazia.
Uma pasta criada pelo utilizador não tem papel special-use, portanto
"role === current" era verdadeiro para todas elas de uma vez.

A exclusão passa a só se aplicar quando há de facto uma pasta actual.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

services/webmail/src/lib/mailCounts.ts

@@ -218,7 +218,13 @@ export function moveTargets(
     if (role === "sent" || role === "drafts") return false;
     if (name === "sent" || name === "drafts") return false;
     // Already here: nothing to do.
-    if (role === current || name === current) return false;
+    //
+    // Guarded on current being non-empty. A folder the user created has no
+    // special-use role, so with an empty current `role === current` was true
+    // for every one of them - and the rules screen, which has no open message
+    // and therefore no current folder, offered a destination list missing
+    // precisely the folders a filing rule is usually written for.
+    if (current !== "" && (role === current || name === current)) return false;
     return Boolean(folder.name);
   });
 }

services/webmail/src/mailCounts.test.ts

@@ -333,3 +333,28 @@ describe("the folders a user made themselves", () => {
     expect(customFolders(undefined)).toEqual([]);
   });
 });
+
+describe("move targets when there is no current folder", () => {
+  const folders = [
+    { special_use: "inbox", name: "INBOX", unread_count: 0, total_count: 1 },
+    { special_use: "sent", name: "Sent", unread_count: 0, total_count: 0 },
+    { special_use: "", name: "Faturas", unread_count: 0, total_count: 0 },
+    { special_use: "", name: "Reports", unread_count: 0, total_count: 0 },
+  ];
+
+  // The rules screen picks a destination without any message being open, so it
+  // has no "current folder" to exclude. Passing an empty string made
+  // `role === current` true for every folder with no special-use role - which
+  // is exactly the folders the user created - so the destination list silently
+  // left out the only folders a filing rule is usually written for.
+  it("offers the custom folders when no folder is excluded", () => {
+    const names = moveTargets(folders, "").map((f) => f.name);
+    expect(names).toContain("Faturas");
+    expect(names).toContain("Reports");
+    expect(names).toContain("INBOX");
+  });
+
+  it("still leaves Sent out", () => {
+    expect(moveTargets(folders, "").map((f) => f.name)).not.toContain("Sent");
+  });
+});