Generalize MCP servers, add model refresh button, add sonnet-5

- MCP: replace fixed single Unity field with a generic list of servers
  ({name, url, token?}); dynamic mcp-config + allowlist glob mcp__*<name>*
  per entry; new mcp-servers-ui.js editor (no data migration)
- Models: frontend refresh button wired to existing POST /api/models/refresh,
  reloads optgroups and restores selection
- Model: add sonnet-5 alias + dropdown option (bare "sonnet" stays 4.6)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

wwwroot/css/form.css

@@ -10,6 +10,17 @@
   margin-top: var(--box-spacing);
 }
 
+.form-label-row {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-top: var(--box-spacing);
+}
+
+.form-label-row label {
+  margin-top: 0;
+}
+
 .more {
   margin: var(--box-spacing) auto;
   cursor: pointer;
@@ -214,6 +225,46 @@
   align-self: flex-start;
 }
 
+.mcp-servers {
+  display: flex;
+  flex-direction: column;
+  gap: var(--badge-spacing);
+}
+
+.mcp-server-item {
+  display: flex;
+}
+
+.mcp-server-fields {
+  flex: 1;
+  display: flex;
+  gap: var(--badge-spacing);
+  overflow: hidden;
+}
+
+.mcp-server-fields .mcp-name {
+  flex: 2;
+}
+
+.mcp-server-fields .mcp-url {
+  flex: 4;
+}
+
+.mcp-server-fields .mcp-token {
+  flex: 3;
+}
+
+.mcp-server-item .remove-mcp-btn {
+  margin-left: var(--badge-spacing);
+  color: var(--dangerous);
+  align-self: center;
+}
+
+.mcp-server-item .remove-mcp-btn:hover {
+  background: var(--dangerous);
+  color: var(--f1-bg);
+}
+
 /* ── Checkbox ── */
 
 label.checkbox-label {