fix(accounts): simplify identity copy tooltips

Show only the copy action in populated username and email cell tooltips instead of repeating values already visible in the table. Preserve explicit accessible button labels and add German and English regression coverage.

tests/settings-view.test.tsx

@@ -834,6 +834,8 @@ describe("account workspace", () => {
       })
     });
     const buttons = findElements(tree, (element) => String(element.props.className || "").includes("settings-account-copy-button"));
+    const copyableCells = findElements(tree, (element) => ["settings-account-username", "settings-account-email"].includes(String(element.props.className || "")))
+      .filter((element) => element.props.title === "Klicken zum Kopieren");
     const username = buttons.find((button) => button.props["aria-label"] === "Benutzername kopieren");
     const email = buttons.find((button) => button.props["aria-label"] === "E-Mail kopieren");
     let stopped = 0;
@@ -843,6 +845,7 @@ describe("account workspace", () => {
     username?.props.onDoubleClick({ stopPropagation: () => { stopped += 1; } });
 
     expect(buttons.some((button) => button.props.children === "—")).toBe(false);
+    expect(copyableCells).toHaveLength(buttons.length);
     expect(copies).toEqual([
       "Benutzername:stored-user",
       "E-Mail:verified@example.test"