TypeScript: drop '.js' extension from '.pb.js' imports

[codecov[bot]]

Codecov Report

Base: 36.85% // Head: 36.85% // No change to project coverage :thumbsup:

Coverage data is based on head (4e8c702) compared to base (cf9eab8). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #204 +/- ## ======================================= Coverage 36.85% 36.85% ======================================= Files 19 19 Lines 795 795 Branches 144 144 ======================================= Hits 293 293 Misses 488 488 Partials 14 14 ``` | [Impacted Files](https://codecov.io/gh/tatethurston/TwirpScript/pull/204?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Tate+Thurston) | Coverage Δ | | |---|---|---| | [.../typescript-fullstack/src/protos/haberdasher.pb.ts](https://codecov.io/gh/tatethurston/TwirpScript/pull/204/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Tate+Thurston#diff-ZXhhbXBsZXMvdHlwZXNjcmlwdC1mdWxsc3RhY2svc3JjL3Byb3Rvcy9oYWJlcmRhc2hlci5wYi50cw==) | `5.97% <ø> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Tate+Thurston). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Tate+Thurston)

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