ci: point website path rule at the coverage source of truth

The exception list named only content, i18n and content.config.ts, but
coverage.exclude also drops test/spec files, stories, .d.ts and
src/test/**. The glob apps/website/src/**/*.{ts,vue} matches all of
them, so 68 files (41 tests, 25 stories, 1 declaration, 1 setup) would
have been told their lines are measured by the website-unit gate when
they are not.

Cite vitest.config.ts as the source of truth rather than only restating
its contents, so the guidance degrades to "go look" instead of silently
becoming wrong when that list changes.

Author: Glary-Bot

.coderabbit.yaml

@@ -131,9 +131,12 @@ reviews:
         status, so new behaviour needs a colocated Vitest test. Treat
         `docs/guidance/vitest.md` as required review context. Flag new
         exported logic that no test exercises.
-        Exception: `src/content/**`, `src/i18n/**` and `src/content.config.ts`
-        are excluded from coverage in `apps/website/vitest.config.ts`, so do
-        not invoke the `website-unit` gate for changes confined to those.
+        This glob is wider than the gate: `coverage.exclude` in
+        `apps/website/vitest.config.ts` is the source of truth, and anything
+        it lists is unmeasured. At time of writing that is `*.test.ts`,
+        `*.spec.ts`, `*.stories.ts`, `*.d.ts`, `src/test/**`,
+        `src/content/**`, `src/i18n/**` and `src/content.config.ts`. Do not
+        cite the `website-unit` gate for changes confined to those.
     - path: 'apps/website/src/**/*.astro'
       instructions: |
         `.astro` files are excluded from coverage because V8 cannot