♻️ Run doc tests outside the coverage gate

An example that exercises a line no hand-written test reaches would let
the `--100` gate pass on documentation alone. Node has no file-level
exclusion, and c8's `--exclude` only filters the report, so run the two
in separate processes: `test:coverage` runs c8 over the tracked tests
only (`git ls-files`, which skips the untracked generated files), and
`test:doc` runs the generated examples without c8. `test:ci` chains
them.

package.json

@@ -61,7 +61,9 @@
         "maintain:outdated": "check-outdated --ignore-pre-releases --ignore-packages @types/node",
         "test": "npm run check:tsc && node --test --strip-types \"src/**/*.test.ts\"",
         "pretest:ci": "npm run create:doc-tests",
-        "test:ci": "c8 --all --include \"src/**/*.ts\" --reporter=text --reporter=lcov --reporter=html --100 node --test --strip-types \"src/**/*.test.ts\"",
+        "test:ci": "npm run test:coverage && npm run test:doc",
+        "test:coverage": "c8 --all --include \"src/**/*.ts\" --reporter=text --reporter=lcov --reporter=html --100 node --test --strip-types $(git ls-files 'src/*.test.ts')",
+        "test:doc": "node --test --strip-types \"src/doc-test/__generated__/*.test.ts\"",
         "test:unit": "node --test --strip-types \"src/**/*.test.ts\"",
         "verify": "npm run check && npm run test:unit",
         "watch": "npm run watch:test",