Add endorse_person_skill and endorse_person_skills tools

[KirillSergeevich]

What

• New tools:
  • endorse_person_skill: endorses one skill of a 1st-degree connection, by its exact name.
  • endorse_person_skills: endorses every skill whose name matches any of the RE2 patterns, or all skills when patterns are omitted. Returns one item per selected skill.
• The tool descriptions tell the agent:
  • skill names are in the profile owner's language;
  • patterns are RE2, case-insensitive and match anywhere;
  • anchor with ^…$ to match a whole name;
  • omit patterns rather than pass [];
  • an already-endorsed skill counts as success and toward the stEndorsements limit;
  • do not retry while the workflow is running.
• The schemas enforce the API's bounds: 1-20 patterns, each 1-200 characters.
• stEndorsements is added to the categories of admin_set_limits and admin_delete_limits.
• @linkedapi/node ^2.3.19; version 2.3.18.

Checks

• npm run lint, npm run typecheck and npm run build pass.
• Both tools were exercised over stdio against a local HTTP stub. tools/list shows their schemas. tools/call sends the right workflow and returns mapped success and failure results. stEndorsements reaches the admin limit endpoints.