update download to include auth

[mgdenno]

Implement teehr client updates for teehr-hub API key authentication and robust paginated fetch behavior under server-side hard row limits.

Required teehr-hub API details

• API key auth header is x-api-key.
• Bearer auth remains supported via Authorization: Bearer <token>.
• Pagination uses limit and offset query parameters.
• GeoJSON collection responses include pagination links in links[], including rel: "next" when another page is available.
• Response includes numberReturned for current page size.
• Server may clamp requested limit based on caller role; client must treat this as expected behavior.
• Auth errors:
  • 401 for invalid/missing credentials on protected routes.
  • 403 for authenticated caller lacking required permissions.

Required teehr client behavior

• Add API key auth mode:
  • Accept API key in client config/session.
  • Send x-api-key on outbound requests when configured.
• Keep existing bearer-token behavior unchanged.
• Add fetch-all pagination mode:
  • Prefer following links[].rel == "next" when present.
  • Fallback to offset pagination when next link is absent.
  • Preserve all filter/query params across page requests.
  • Continue until no next page exists.
• Hard-limit compatibility:
  • Do not stop after first page just because returned rows are less than requested limit.
  • Continue paging whenever a next page is indicated.

Required acceptance criteria

• Client can call protected teehr-hub endpoints using x-api-key.
• Fetch-all mode retrieves complete multi-page datasets.
• Client handles server-clamped first page without truncating overall result set.
• Tests cover:
  • API key auth success/failure.
  • Next-link pagination.
  • Offset fallback pagination.
  • Clamped-first-page scenario.