feat: notify document updates over websocket

apps/server/internal/httpserver/static/site.css

@@ -177,6 +177,41 @@ code {
   max-width: 100%;
 }
 
+.version-notice {
+  position: fixed;
+  right: 1rem;
+  bottom: 1rem;
+  display: flex;
+  align-items: center;
+  gap: 0.85rem;
+  max-width: min(28rem, calc(100vw - 2rem));
+  padding: 0.75rem 0.85rem;
+  border: 1px solid var(--border);
+  border-radius: var(--radius-sm);
+  background: var(--panel-strong);
+  box-shadow: var(--shadow);
+}
+
+.version-notice[hidden] {
+  display: none;
+}
+
+.version-notice p {
+  margin: 0;
+  color: var(--text);
+}
+
+.version-notice button {
+  min-height: 2.2rem;
+  padding: 0 0.8rem;
+  border: 0;
+  border-radius: var(--radius-sm);
+  color: white;
+  background: var(--accent);
+  font: 700 0.9rem/1 ui-monospace, SFMono-Regular, monospace;
+  cursor: pointer;
+}
+
 @media (max-width: 720px) {
   .site-header__inner {
     flex-direction: column;
@@ -191,4 +226,3 @@ code {
     padding: 1.25rem;
   }
 }
-