feat: added Secure Crypto Vault to starter_code

[Chirantan112]

Summary

Added a professional-grade "Secure Crypto Vault" template to the starter_code directory. This project provides a functional CLI utility that demonstrates industry-standard security implementations, specifically focusing on AES-256-GCM authenticated encryption and PBKDF2 key derivation.

---

Related Issue

Closes #319

---

Type of Change

• Feature — adds new functionality
• Documentation — updates docs, README, or code comments only

---

What Was Changed

File	Change made
starter_code/secure-vault/vault.py	Implementation of core vault logic, encryption/decryption, and CLI menu
starter_code/secure-vault/requirements.txt	Added necessary cryptography library dependency
starter_code/secure-vault/README.md	Created project documentation, setup instructions, and security specs

---

How to Test This PR

1. Clone this branch: git checkout main
2. Navigate to the project directory: cd starter_code/secure-vault
3. Install dependencies: pip install -r requirements.txt
4. Run the app: python vault.py
5. Validation:
   • Create a Master Password (verify input masking).
   • Add a test service entry.
   • Retrieve and decrypt the entry to verify logic.
   • Verify that sensitive data is stored as encrypted hex strings in vault.json.

---

Self-Review Checklist

• I have read CONTRIBUTING.md and followed all guidelines
• My branch name follows the convention
• I have verified the code runs locally without errors
• I have not introduced any print() debug statements
• I have not modified files outside the scope of the linked issue

---

Notes for Reviewer

• Follows the organizational pattern of the starter_code directory.
• Implementation uses cryptography.hazmat to ensure high-security primitives (AES-GCM).
• Key derivation (PBKDF2) uses 600,000 iterations to align with OWASP password storage recommendations.
• Designed as a "starter" project to help GSSoC contributors learn about secure credential management.

[vercel]

@Chirantan112 is attempting to deploy a commit to the komalsony234-1530's projects Team on Vercel.

A member of the Team first needs to authorize it.