feat: implement authentication modal and update dashboard password handling

src/templates/static/css/dashboard.css

@@ -1168,6 +1168,139 @@ tbody {
     opacity: 1;
 }
 
+/* Auth Modal */
+.auth-modal {
+    position: fixed;
+    z-index: 1000;
+    left: 0;
+    top: 0;
+    width: 100%;
+    height: 100%;
+    background-color: rgba(0, 0, 0, 0.7);
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    backdrop-filter: blur(4px);
+}
+.auth-modal-content {
+    background-color: #161b22;
+    border: 1px solid #30363d;
+    border-radius: 12px;
+    width: 400px;
+    max-width: 90vw;
+    box-shadow: 0 16px 48px rgba(0, 0, 0, 0.6);
+    animation: authModalIn 0.2s ease-out;
+}
+@keyframes authModalIn {
+    from { opacity: 0; transform: scale(0.95) translateY(-10px); }
+    to { opacity: 1; transform: scale(1) translateY(0); }
+}
+.auth-modal-header {
+    padding: 20px 24px 16px;
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    border-bottom: 1px solid #30363d;
+}
+.auth-modal-title {
+    display: flex;
+    align-items: center;
+    gap: 10px;
+    color: #58a6ff;
+}
+.auth-modal-title h3 {
+    margin: 0;
+    font-size: 16px;
+    font-weight: 600;
+    color: #e6edf3;
+}
+.auth-modal-close {
+    color: #8b949e;
+    font-size: 24px;
+    font-weight: bold;
+    cursor: pointer;
+    line-height: 20px;
+    transition: color 0.2s;
+}
+.auth-modal-close:hover {
+    color: #c9d1d9;
+}
+.auth-modal-body {
+    padding: 24px;
+}
+.auth-modal-description {
+    margin: 0 0 20px;
+    color: #8b949e;
+    font-size: 14px;
+    line-height: 1.5;
+}
+.auth-modal-input-group {
+    margin-bottom: 20px;
+}
+.auth-modal-input {
+    width: 100%;
+    padding: 10px 14px;
+    background: #0d1117;
+    border: 1px solid #30363d;
+    border-radius: 6px;
+    color: #e6edf3;
+    font-size: 14px;
+    outline: none;
+    transition: border-color 0.2s, box-shadow 0.2s;
+    box-sizing: border-box;
+}
+.auth-modal-input:focus {
+    border-color: #58a6ff;
+    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.15);
+}
+.auth-modal-input-error {
+    border-color: #f85149;
+}
+.auth-modal-input-error:focus {
+    border-color: #f85149;
+    box-shadow: 0 0 0 3px rgba(248, 81, 73, 0.15);
+}
+.auth-modal-error {
+    margin: 8px 0 0;
+    color: #f85149;
+    font-size: 13px;
+}
+.auth-modal-footer {
+    display: flex;
+    justify-content: flex-end;
+    gap: 10px;
+}
+.auth-modal-btn {
+    padding: 8px 20px;
+    border-radius: 6px;
+    font-size: 14px;
+    font-weight: 500;
+    cursor: pointer;
+    border: 1px solid transparent;
+    transition: all 0.2s;
+}
+.auth-modal-btn-cancel {
+    background: transparent;
+    border-color: #30363d;
+    color: #8b949e;
+}
+.auth-modal-btn-cancel:hover {
+    background: #21262d;
+    color: #c9d1d9;
+}
+.auth-modal-btn-submit {
+    background: #238636;
+    color: #fff;
+    border-color: rgba(240, 246, 252, 0.1);
+}
+.auth-modal-btn-submit:hover {
+    background: #2ea043;
+}
+.auth-modal-btn-submit:disabled {
+    opacity: 0.6;
+    cursor: not-allowed;
+}
+
 /* Attack Types Cell Styling */
 .attack-types-cell {
     max-width: 280px;