add session open/closed state to prevent modifications

static/css/style.css

@@ -760,6 +760,74 @@ td a:hover {
     align-items: stretch;
 }
 
+.button-row {
+    display: flex;
+    gap: 0.75rem;
+    flex-wrap: wrap;
+}
+
+.secondary-button {
+    appearance: none;
+    border: 1px solid rgba(255, 255, 255, 0.12);
+    background: rgba(255, 255, 255, 0.04);
+    color: var(--text-strong);
+    border-radius: 12px;
+    padding: 0.8rem 1rem;
+    font: inherit;
+    font-weight: 600;
+    cursor: pointer;
+}
+
+.secondary-button:hover {
+    background: rgba(255, 255, 255, 0.07);
+}
+
+.status-badge {
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    min-width: 5.5rem;
+    padding: 0.35rem 0.65rem;
+    border-radius: 999px;
+    font-size: 0.78rem;
+    font-weight: 700;
+    letter-spacing: 0.06em;
+    text-transform: uppercase;
+}
+
+.status-open {
+    color: #f59e0b;
+    background: rgba(245, 158, 11, 0.12);
+    border: 1px solid rgba(245, 158, 11, 0.24);
+}
+
+.status-closed {
+    color: #94a3b8;
+    background: rgba(148, 163, 184, 0.1);
+    border: 1px solid rgba(148, 163, 184, 0.2);
+}
+
+.inline-action-form {
+    margin: 0;
+}
+
+.table-action-button {
+    appearance: none;
+    border: 1px solid rgba(255, 255, 255, 0.1);
+    background: rgba(255, 255, 255, 0.04);
+    color: var(--text-strong);
+    border-radius: 10px;
+    padding: 0.45rem 0.7rem;
+    font: inherit;
+    font-size: 0.88rem;
+    font-weight: 600;
+    cursor: pointer;
+}
+
+.table-action-button:hover {
+    background: rgba(255, 255, 255, 0.07);
+}
+
 @media (max-width: 980px) {
     .site-shell {
         width: min(100% - 24px, 100%);