fix(merge): post-merge cleanup after upstream/master backport

- restore server/src/services/github-fetch.ts (re-added by upstream; dev's
  history had deleted it via 80f7d827)
- drop stale companySkillUpdateAuthSchema export from shared/index.ts
  (upstream removed the validator we took with --theirs)
- regenerate pnpm-lock.yaml for the merged workspace

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shared/src/index.ts

@@ -1087,7 +1087,6 @@ export {
   companySkillAuditFindingSchema,
   companySkillAuditResultSchema,
   companySkillImportSchema,
-  companySkillUpdateAuthSchema,
   companySkillProjectScanRequestSchema,
   companySkillProjectScanSkippedSchema,
   companySkillProjectScanConflictSchema,