zod fails to compile under perry.compilePackages: cross-module class re-exports unresolved

[proggeramlug]

Surfaced by the new npm-package sweep harness (`scripts/npm_compile_sweep.sh`, added under #805). zod is in the tier1 list — high-leverage "should compile today" target.

Repro

```bash
mkdir /tmp/perry-zod && cd /tmp/perry-zod
cat > package.json <<'JSON'
{"name":"d","private":true,"type":"module","dependencies":{"zod":"*"},"perry":{"compilePackages":["zod"]}}
JSON
npm install
cat > main.ts <<'TS'
import { z } from "zod";
console.log(z.object({ a: z.string() }).parse({ a: 'hi' }).a);
TS
perry main.ts -o out
```

Failure mode (v0.5.914)

Link step emits dozens of undefined symbols. The instructive ones:

```
"___perry_wrap_perry_fn_node_modules_zod_src_index_ts__z", referenced from:
_main in main_ts.o
"___perry_wrap_perry_fn_node_modules_zod_src_v4_core_regexes_ts__null", referenced from:
_perry_closure_node_modules_zod_src_v4_core_schemas_ts__98 in node_modules_zod_src_v4_core_schemas_ts.o
"___perry_wrap_perry_fn_node_modules_zod_src_v4_core_regexes_ts__undefined", referenced from:
perry_closure_node_modules_zod_src_v4_core_schemas_ts__96 in node_modules_zod_src_v4_core_schemas_ts.o
"perry_fn_node_modules_zod_src_v4_core_checks_ts\$ZodCheck", referenced from:
perry_closure_node_modules_zod_src_v4_core_schemas_ts__323 in node_modules_zod_src_v4_core_schemas_ts.o
"perry_fn_node_modules_zod_src_v4_core_core_ts\$constructor", referenced from:
_node_modules_zod_src_v4_classic_errors_ts__init in node_modules_zod_src_v4_classic_errors_ts.o
```

Two distinct sub-bugs in the same repro

1. `__regexes_ts__null` / `__regexes_ts__undefined` — zod's `regexes.ts` re-exports patterns under names like `null` and `undefined`. Perry's codegen emits `_perry_wrap_perry_fn__null` references but the producing module never emits the corresponding definition (likely the codegen treats `null`/`undefined` as keywords and skips defining the wrapper). Renaming the exports in user code shouldn't be necessary — zod is unmodified.

2. `core_checks_ts$ZodCheck` etc — class symbols prefixed with `$`. These look like the same class-export-not-resolved family as Linker: unresolved _perry_fn_..._render for V8-fallback modules referenced from main #678 (V8-fallback / re-export rename) and fix(codegen): #678 — re-export rename resolves to origin export name #785 (re-export origin name). But the failing module is the producer (`core/checks.ts`), not the re-exporting layer, so this is a different breakage.

Suggested triage

The npm-sweep CSV will pick up regressions/improvements automatically once this lands. Tier1 should reach pass once both sub-bugs close.

Part of #793 + #805. Surfaced by the #805 sweep harness on its first tier1 run.

[proggeramlug]

Closing — landed in PR #883 (fix(codegen): #836 — emit producer aliases for $-prefixed re-exports and namespace wrappers) merged 2026-05-16. Validated via the canonical zod repro: import { z } from 'zod'; console.log(z.object({a:z.string()}).parse({a:'hi'}).a) now compiles and runs end-to-end against npm-installed zod under perry.compilePackages. Regression test in test-files/test_issue_836_zod_class_reexports.ts byte-matches node --experimental-strip-types. The remaining v4/locales/en.ts anonymous export default function () {…} was a separate gap, closed in PR #885.