✨ Compile doc code fences into tests

Every `ts`-tagged fence in README.md / CONTRIBUTING.md now becomes an
executed `node:test` case in a gitignored generated file, so a
documented example cannot drift from the API. The generator hoists and
merges the leading imports, rewrites the library specifier to the
`#test-tiny-pattern-ts` alias, and rejects a fence with no describing
paragraph or one that re-imports a prelude module.

CI regenerates via `pretest:ci`; `create:doc-tests` runs the generator,
formats, then typechecks the output against a scoped tsconfig that
relaxes `noUnusedLocals`. c8's default excludes already omit the
generated `*.test.ts`, so `test:ci` is unchanged.

src/doc-test/tsconfig.json

@@ -0,0 +1,10 @@
+{
+    "extends": "../../tsconfig.json",
+    "compilerOptions": {
+        "noEmit": true,
+        "noUnusedLocals": false,
+        "noUnusedParameters": false
+    },
+    "include": ["__generated__/**/*.test.ts"],
+    "exclude": []
+}