feat(02-03): wire SkillService into ServiceGraph and preload bridge

- Add lazy SkillService creation in ServiceGraph with getOrCreateSkillService getter
- Pass skillService to registerDomainHandlers in main-runtime-support
- Add 7 skill operations to preload bridge (importSkill, listSkills, getSkillDetail, deleteSkill, assignSkillToAgent, removeSkillFromAgent, checkSkillUpdate)
- Add skillService cleanup in app lifecycle shutdown

src/main/main-runtime-support.ts

@@ -168,6 +168,7 @@ export function createMainRuntimeSupport(state: MainRuntimeState) {
       bootstrapOnboarding: (input) => requireOnboardingService().bootstrapOnboarding(input),
       getBrowserActions: () => requireServiceGraph().getBrowserActionService(),
       randomFallbackCompanyId: () => requireConnectorHealthService().randomFallbackCompanyId(),
+      skillService: requireServiceGraph().getOrCreateSkillService(),
     });
   }