✨ 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.

tsconfig.json

@@ -8,5 +8,6 @@
         "allowImportingTsExtensions": true,
         "verbatimModuleSyntax": true
     },
-    "include": ["src", "scripts"]
+    "include": ["src", "scripts"],
+    "exclude": ["src/doc-test"]
 }