Add copy buttons to code blocks and tool input and output

web/style.css

@@ -625,6 +625,7 @@ button.compact.danger {
 .md ol,
 .md blockquote,
 .md pre,
+.md .copyable,
 .md .md-table {
   margin: 0 0 8px;
 }
@@ -670,6 +671,7 @@ button.compact.danger {
 }
 
 .md pre.md-code {
+  margin: 0;
   background: var(--surface);
   border: 1px solid var(--border);
   border-radius: 6px;
@@ -822,11 +824,42 @@ button.compact.danger {
   border: 1px solid var(--border);
   padding: 6px 8px;
   border-radius: 6px;
-  margin: 6px 0;
   max-height: 320px;
   overflow: auto;
 }
 
+.tool .copyable,
+.tool-result .copyable {
+  margin: 6px 0;
+}
+
+.copyable {
+  position: relative;
+}
+
+.copyable .copy {
+  position: absolute;
+  top: 4px;
+  right: 4px;
+  padding: 0 6px;
+  border-radius: 4px;
+  font-size: 11px;
+  color: var(--muted);
+  background: var(--raised);
+  opacity: 0;
+}
+
+.copyable:hover .copy,
+.copyable .copy:focus-visible {
+  opacity: 1;
+}
+
+@media (hover: none) {
+  .copyable .copy {
+    opacity: 1;
+  }
+}
+
 .tool-result.pending {
   color: var(--muted);
   font-style: italic;