Add basics/counter/poseidon

[adpthegreat]

• added poseidon counter program to basics/counter folder
• updated dependencies to use latest versions of anchor
• used pnpm in place of yarn, replaced all instances of yarn with pnpm
• wrote tests

My second PR : #150

[heyAyushh]

Thanks for your submission! To verify the technical implementation, please complete these steps:

1. Merge the main branch into your PR to get the latest updates
2. Run pnpm fix at the project root for consistent code style
3. Ensure your implementation includes:
   • Transpiled Anchor program in the programs folder
   • TypeScript files in the ts-programs folder
4. Run poseidon sync to synchronize program ID and keys
5. Run cargo fmt and cargo clippy for Rust code quality
6. Push your changes

Please note: This review is to verify technical completeness of the submission

Let me know once you've completed these steps and I'll review again. Thanks!