Fix profile e2e test flakiness by waiting for API response

- Wait for PUT /api/profile response before reloading page
- Wait for network idle after save completes
- Reuse existing saveButton variable instead of redeclaring
- All 40 e2e tests passing

frontend/e2e/profile.spec.ts

@@ -196,9 +196,21 @@ test.describe("Profile - Form Behavior", () => {
 
     // Clear the field - use clear() instead of fill("") for reliable clearing
     await page.locator("#telegram").clear();
-    await page.click('button:has-text("Save Changes")');
+
+    // Wait for save button to be enabled (indicates form detected the change)
+    await expect(saveButton).toBeEnabled({ timeout: 2000 });
+
+    // Set up response listener before clicking save
+    const responsePromise = page.waitForResponse(
+      (resp) => resp.url().includes("/api/profile") && resp.request().method() === "PUT"
+    );
+
+    await saveButton.click();
+
+    // Wait for save to complete
+    await responsePromise;
     await expect(page.getByText(/saved successfully/i)).toBeVisible();
-    await expect(page.getByText(/saved successfully/i)).not.toBeVisible({ timeout: 5000 });
+    await page.waitForLoadState("networkidle");
 
     // Reload and wait for page to fully load before checking
     await page.reload();