fix(models): support Node 26 type stripping - #4076

Summary

npm run check:model-metadata fails on supported Node 26 releases before it can validate either committed generated module.

Node 26 removed the transform mode from module.stripTypeScriptTypes(), while the metadata checker still requested it. The generated metadata and pricing modules use erasable TypeScript syntax, so the supported strip mode is sufficient on both Node 22.19 and Node 26.

Use strip and add a regression test that converts and imports both committed generated modules before asserting their runtime exports.

Evidence

Before (Node v26.5.0):
TypeError [ERR_INVALID_ARG_VALUE]: The property 'options.mode' must be one of: 'strip'. Received 'transform'
    at loadTypeScriptModule (scripts/sync-model-metadata.mjs:500:22)

After (Node v26.5.0):
✔ loads the committed generated TypeScript modules
ℹ pass 1
ℹ fail 0

After (Node v22.19.0):
ok 1 - loads the committed generated TypeScript modules
# pass 1
# fail 0

Verification

• npm run check:model-metadata on Node 26.5.0
• npx --yes node@22.19.0 scripts/sync-model-metadata.mjs --check
• node --test scripts/sync-model-metadata.test.mjs — 9/9 passed
• npm run lint
• npm run format:check
• node scripts/asf-license-headers.mjs check
• git diff --check

Full build and typecheck were not run for this script-only draft.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex implemented the Node compatibility change, regression test, and PR description.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No