fix: technical debts left by the Sites, Authors and SEO slices, plus backend support for the new Sites and Authors pagination

docs/development.md

@@ -72,6 +72,11 @@ task clean           # remove bin/, tmp/ and the built SPA
 - All Go tests live in [`test/`](../test) (package `test`, black-box). They use in-memory fakes of the domain `Repository` interfaces, so they need no database, SMTP server or network.
 - HTTP-level tests use `net/http/httptest` against a chi router. Call `validator.InitValidator()` before invoking a handler.
 - SPA component tests use Vitest + Vue Test Utils (`task test:web`). `task lint:web` runs eslint and a type check.
+- A few tests open a real SQLite file in a temporary directory (the chunked id lookups, the slug backfill and the `?seo=` measurement). They never touch the real database.
+- The tests that need a real MySQL, MariaDB or PostgreSQL server skip themselves when `RENEWCMS_TEST_MYSQL_DSN` or `RENEWCMS_TEST_POSTGRES_DSN` is unset. No CI exists, so run them by hand before a release that touches the repositories:
+  - `task test:mysql` runs `mysql:8.4` then `mariadb:11` in Docker, and `task test:postgres` runs `postgres:16` then `postgres:17`. Docker is required; the tasks start and remove the containers. Extra arguments go after `--`, for example `task test:postgres -- -run Postgres.*Chunked -v`.
+  - To use your own server on a scratch database: `RENEWCMS_TEST_MYSQL_DSN='user:pass@tcp(host:3306)/db' go test -tags nofrontend ./test/... -run MySQL -count=1`, or `RENEWCMS_TEST_POSTGRES_DSN='postgres://user:pass@host:5432/db?sslmode=disable' go test -tags nofrontend ./test/... -run Postgres -count=1`.
+  - `TestMySQLChunkedLookups` and `TestPostgresChunkedLookups` check that the batched `IN` lookups of the article repository (500 ids per batch) return the same rows as SQLite.
 
 ## Visual check against the design