feat(skills): add ClawHub registry catalog parser and loader

src/skills/index.ts

@@ -14,5 +14,7 @@ export { buildInstallerPlan } from './planner.js';
 export type { InstallerPlan, InstallerPlanStep, InstallerPlanSkip, InstallerPlanningOptions } from './planner.js';
 export { SkillRegistry } from './registry.js';
 export { SkillInstaller } from './installer.js';
+export { loadSkillRegistryCatalog, parseSkillRegistryCatalog } from './registrySource.js';
+export type { SkillRegistryCatalog, SkillRegistryEntry, SkillRegistrySource, SkillRegistryLoadOptions } from './registrySource.js';
 export { SkillsWatcher } from './watcher.js';
 export type { SkillsWatcherConfig, SkillsWatcherEvent } from './watcher.js';