fix(accounts): separate Debrid-Link username and email

Persist the username and email returned by the Debrid-Link account endpoint as distinct identity fields and project them into their matching account-table columns. Migrate cached legacy statuses that stored a username in the email field, preserve both fields through renderer validation and sanitization, and cover API responses with and without an email address.

tests/account-check.test.ts

@@ -81,14 +81,23 @@ describe("checkMegaDebridAccount", () => {
 });
 
 describe("checkDebridLinkKey", () => {
-  it("reports valid + premium from premiumLeft seconds", async () => {
-    const premiumLeft = 60 * 24 * 60 * 60;
-    mockFetchOnce(200, { success: true, value: { username: "u", accountType: 1, premiumLeft } });
-    const st = await checkDebridLinkKey(debridLinkKey(), undefined, NOW);
-    expect(st.valid).toBe(true);
-    expect(st.isPremium).toBe(true);
-    expect(st.premiumUntilMs).toBe(NOW + premiumLeft * 1000);
-  });
+  it("reports valid + premium from premiumLeft seconds", async () => {
+    const premiumLeft = 60 * 24 * 60 * 60;
+    mockFetchOnce(200, { success: true, value: { username: "u", email: "u@example.test", accountType: 1, premiumLeft } });
+    const st = await checkDebridLinkKey(debridLinkKey(), undefined, NOW);
+    expect(st.valid).toBe(true);
+    expect(st.isPremium).toBe(true);
+    expect(st.premiumUntilMs).toBe(NOW + premiumLeft * 1000);
+    expect(st.username).toBe("u");
+    expect(st.email).toBe("u@example.test");
+  });
+
+  it("does not present a Debrid-Link username as an email address", async () => {
+    mockFetchOnce(200, { success: true, value: { username: "xsucukde5", accountType: 0, premiumLeft: 0 } });
+    const st = await checkDebridLinkKey(debridLinkKey(), undefined, NOW);
+    expect(st.username).toBe("xsucukde5");
+    expect(st.email).toBeUndefined();
+  });
 
   it("reports valid but free (premiumLeft 0, accountType 0)", async () => {
     mockFetchOnce(200, { success: true, value: { username: "u", accountType: 0, premiumLeft: 0 } });