feat(plugins): add command and menu contributions with bottom dock

apps/desktop/src/lib/plugins/pluginUiHtmlCache.ts

@@ -0,0 +1,28 @@
+// The inlined plugin ui document is multiple megabytes; rebuilding it per
+// workbench instance (every dock panel, every tab) re-reads the entry through
+// the bridge and re-parses it each time. Module scope is the point: the cache
+// is shared by every PluginWorkbenchHost instance, so only the first boot of a
+// plugin version pays the read/decode/inline pipeline.
+const cache = new Map<string, { html: string; entryDirectory: string }>();
+const LIMIT = 4;
+
+export function getCachedPluginUiHtml(key: string): { html: string; entryDirectory: string } | undefined {
+  const hit = cache.get(key);
+  if (!hit) return undefined;
+  // Map iterates oldest-first; re-inserting makes the just-read entry the
+  // newest survivor of an eviction.
+  cache.delete(key);
+  cache.set(key, hit);
+  return hit;
+}
+
+export function setCachedPluginUiHtml(key: string, value: { html: string; entryDirectory: string }): void {
+  cache.delete(key);
+  cache.set(key, value);
+  while (cache.size > LIMIT) cache.delete(cache.keys().next().value as string);
+}
+
+/** Test and plugin-uninstall escape hatch. */
+export function clearPluginUiHtmlCache(): void {
+  cache.clear();
+}