Add Multi-CLI Plan feature and corresponding JSON schema

- Introduced a new navigation item for "Multi-CLI Plan" in the dashboard template.
- Created a new JSON schema for "Multi-CLI Discussion Artifact" to facilitate structured discussions and decision-making processes.

ccw/src/templates/dashboard-css/21-cli-toolmgmt.css

@@ -699,6 +699,28 @@
   color: hsl(var(--foreground));
 }
 
+.file-browser-path:focus {
+  outline: none;
+  border-color: hsl(var(--primary));
+  box-shadow: 0 0 0 2px hsl(var(--primary) / 0.2);
+}
+
+.file-browser-drives {
+  display: flex;
+  gap: 0.25rem;
+}
+
+.btn-xs {
+  padding: 0.25rem 0.5rem;
+  font-size: 0.6875rem;
+  border-radius: 0.25rem;
+}
+
+.drive-btn {
+  font-family: monospace;
+  font-weight: 600;
+}
+
 .file-browser-hidden-toggle {
   display: flex;
   align-items: center;