Call the registered canonical-authority helper

[chubes4]

Problem

Extra Chill SEO checks for and calls ec_get_canonical_authority_url(), but Extra Chill Network exports extrachill_get_canonical_authority_url(). The checks are always false, silently bypassing configured cross-site taxonomy authority.

Required outcome

Call the existing registered public helper directly; do not add a compatibility wrapper.

Tests

• Location archives remain intentionally self-canonical.
• Configured venue, festival, and artist authority resolves to the network-owned canonical URL.
• Schema and Open Graph consume the same authority.