fix: remove login container animation causing upward drift on refresh

- Remove automatic slideUp animation from login container
- Set stable positioning with fixed opacity and transform
- Prevent visual jumping/movement on page refresh
- Improve login page stability and user experience

The login form will now remain in a consistent position without
unwanted animation triggers on page reload.

static/login.html

@@ -43,6 +43,13 @@
             width: 100%;
             max-width: 420px;
             position: relative;
+            /* Remove animation to prevent upward drift on refresh */
+            opacity: 1;
+            transform: translateY(0);
+        }
+
+        /* Optional: Add animation only on first visit */
+        .tt-login-container.animate-in {
             animation: slideUp 0.6s ease-out;
         }