Extract static smoketest modules into a nested workspace at
crates/smoketests/modules/ that is pre-compiled during warmup.
This eliminates per-test WASM compilation overhead.
Key changes:
- Add 38 precompiled module crates in nested workspace
- Add module registry (src/modules.rs) for WASM path lookup
- Add precompiled_module() builder and use_precompiled_module() method
- Update xtask warmup to build nested workspace
- Migrate all static tests to use precompiled modules
- Tests using precompiled modules run in ~0.5-3s vs ~4-7s before
Tests that need runtime compilation (auto_migration, detect_wasm_bindgen,
intentionally-broken modules) continue to use module_code().
=