* ci: make hot-path coverage gates required PR checks
Remove continue-on-error from frontend and Rust coverage jobs now that
the hot-path lists have stabilized; update docs and script headers.
* docs: note hard coverage gates in changelog and credits (PR #921)
* chore: drop credits entry for CI-only PR #921
Contributor credits are for user-visible work, not infra toggles.
Document where to ask questions, local commands that mirror CI, PR
expectations, caution around disruptive UI, stability of the Tauri
Rust-frontend contract, and impact of on-disk settings changes.
Link the guide from the README Development section.