refactor: configure @/* and @mdb/* path aliases and clean up deep relative imports

[aminamos]

Summary:

Resolves #195.
Configures @/* (pointing to src/*) and @mdb/* (pointing to src/app/*) path aliases in tsconfig.json and jest.config.ts, eliminating brittle multi-level relative path traversal.

Expected behavior:

Clean, maintainable module imports throughout deep route folders.

Testing tips:

1. Checkout refactor/195-import-aliases.
2. Run yarn test to confirm module resolution works in Jest and TypeScript.

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• Add or update any needed documentation to the repo
• Format the title like "feat: [new feature short description]". Title must follow the Conventional Commit Specification(https://www.conventionalcommits.org/en/v1.0.0/).
• Linked all relevant issues
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