♻️ Drop assert imports from doc fences

`assert` is the sole injected exception: the generated test always binds
it, so a fence must not import it. Revert the README imports and the
generator's node:assert merging; the fences keep the assigned variables
and `assert.equal` calls, and the generator again rejects a fence that
imports node:assert.

development/docs.md

@@ -38,9 +38,8 @@ Compile every `ts / `typescript fence in the prose docs into a real
   `docs/` + `examples/` list is the natural extension; `development/` must never
   be scanned (its fences are illustrative, not compilable).
 - The generator hoists and merges leading imports, rewrites `tiny-pattern-ts` to
-  the `#test-tiny-pattern-ts` source alias, merges an example's `node:assert`
-  import into the prelude assert, and rejects an example that imports
-  `node:test` (the prelude binds `test`). Titles are the
+  the `#test-tiny-pattern-ts` source alias, and rejects an example that imports
+  `node:assert` / `node:test` (the prelude already binds both). Titles are the
   immediately preceding paragraph; a fence with no such paragraph is a fatal
   error, which keeps every example described.
 - `oxlint src/doc-test` reports "No files found" because the generated