feat(10-01): add skillRegistry API client and query keys

- Create ui/src/api/skillRegistry.ts with typed methods for all 7 endpoints
- Use two-segment URL paths (/sourceId/slug) for Express 5 compatibility
- Add skillRegistry namespace to queryKeys.ts (list/detail/versions)

ui/src/api/skillRegistry.ts

@@ -0,0 +1,46 @@
+import { api } from "./client";
+
+export type SkillListItem = {
+  id: string;
+  name: string;
+  description: string | null;
+  sourceId: string;
+  category: string | null;
+  activeVersionId: string | null;
+  removedAt: number | null;
+  averageRating: number | null;
+  ratingCount: number | null;
+};
+
+export type SkillVersion = {
+  id: string;
+  skillId: string;
+  version: string;
+  fetchedAt: number;
+  cacheDir: string | null;
+};
+
+function skillPath(skillId: string): string {
+  const [sourceId, ...slugParts] = skillId.split("/");
+  const slug = slugParts.join("/");
+  return `/skill-registry/skills/${sourceId}/${slug}`;
+}
+
+export const skillRegistryApi = {
+  list: (opts?: { includeRemoved?: boolean }) =>
+    api.get<SkillListItem[]>(
+      `/skill-registry/skills${opts?.includeRemoved ? "?includeRemoved=true" : ""}`,
+    ),
+  getById: (skillId: string) =>
+    api.get<SkillListItem>(skillPath(skillId)),
+  getVersions: (skillId: string) =>
+    api.get<SkillVersion[]>(`${skillPath(skillId)}/versions`),
+  fetch: () =>
+    api.post<{ fetched: number; errors: string[] }>("/skill-registry/fetch", {}),
+  install: (skillId: string, agentSkillsDir: string) =>
+    api.post(`${skillPath(skillId)}/install`, { agentSkillsDir }),
+  rollback: (skillId: string, versionId: string, agentSkillsDir: string) =>
+    api.post(`${skillPath(skillId)}/rollback`, { versionId, agentSkillsDir }),
+  remove: (skillId: string) =>
+    api.delete(skillPath(skillId)),
+};

ui/src/lib/queryKeys.ts

@@ -134,6 +134,11 @@ export const queryKeys = {
   skills: {
     available: ["skills", "available"] as const,
   },
+  skillRegistry: {
+    list: ["skill-registry", "skills"] as const,
+    detail: (skillId: string) => ["skill-registry", "skills", skillId] as const,
+    versions: (skillId: string) => ["skill-registry", "skills", skillId, "versions"] as const,
+  },
   plugins: {
     all: ["plugins"] as const,
     examples: ["plugins", "examples"] as const,