chore: fix typo'd source filenames strerak.module.ts and enviroment.validation.ts

[phertyameen]

Summary

Two files ship with typos baked into their filenames, forcing every importer to reproduce the typo:

1. backend/src/streak/strerak.module.ts — imported in app.module.ts as:

   import { StreakModule } from './streak/strerak.module';

   (the class inside is correctly named StreakModule)
2. backend/src/config/enviroment.validation.ts - "environment" is misspelled.

Why bother

Filename typos propagate into every import site, IDE quick-fixes, and grep-based navigation. They also look sloppy to new contributors evaluating the project. Renaming is mechanical: git mv + update importers + confirm tsc --noEmit.

Acceptance criteria

• streak/strerak.module.ts renamed to streak/streak.module.ts; app.module.ts updated.
• config/enviroment.validation.ts renamed to config/environment.validation.ts; importers updated.
• Backend builds and type-checks clean after rename.

[obswrld]

I would like to work on this Issue