v0.7.6 - housekeeping (CI gate, ruff, Node-24, taxonomy, PSI-CrUX note)

Housekeeping batch, no new tools or prompts (52 tools / 13 prompts). psi_analyze + lighthouse_budget gain an additive field_data_note pointing to crux_snapshot/crux_history (PSI CrUX field-data deprecation). technical_seo_audit + structured_data_audit descriptions now name their lane and cross-reference the other audit prompts. New ci.yml runs pytest + ruff on push/PR; pre-existing ruff debt cleared (ruff pinned in dev extra); release.yml opts JS actions onto Node 24 ahead of the 2026-06-16 runner cutover. README tool descriptions synced to the v0.7.x surface. See CHANGELOG.md.