Added basics/realloc/poseidon

[ritikbhatt20]

• added an example for realloc Poseidon program in the /basics/realloc/poseidon directory.

Note: Dynamic reallocation is currently unsupported in Poseidon's framework thus this example uses fixed-sized fields. I have raised an issue to request support for this feature in Poseidon: [Poseidon Issue #22] (https://github.com/Turbin3/poseidon/issues/22).

• once Poseidon adds support for dynamic reallocation, will update this code accordingly to utilize the Poseidon transpiler.
• replaced all occurrences of yarn with pnpm to maintain consistency across the project.
• wrote tests using both the Solana Bankrun framework and Anchor's native testing framework.
• executed pnpm fix to ensure code quality.
• committed the pnpm-lock.yaml file to the repository.

[ritikbhatt20]

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!

gm @heyAyushh ,

I have refactored the changes according to new Poseidon Str type.. plus

I've completed the requested steps:

Merged main into my branch. Ran pnpm fix. Verified the implementation includes the transpiled Anchor program and TypeScript files. Synchronized program ID Ran cargo fmt and cargo clippy for Rust code quality. Pushed all updates. Please review again. Thank you!