feat: Contract integrations and feature implementations

[bitcoindev817-hue]

Description

This PR implements multiple critical MVP contract features to elevate the SoroTask platform capabilities:

• Hierarchical Task Grouping and Batch Management: Implemented functionality allowing users to group tasks into portfolios. Users can now pause, resume, or fund entire groups of tasks with a single transaction.
• Native Token Integration and Tokenomics: Designed and integrated native token features and comprehensive tokenomics into the contract architecture.
• Verifiable Random Function (VRF) Integration: Integrated on-chain randomness using a VRF oracle, enabling tasks to incorporate provably fair random conditions and selection processes.
• Automated Yield Harvesting Strategies: Built specialized, gas-optimized target contracts designed specifically to automatically harvest and compound yield from major Soroban DeFi protocols.

Related Issues

Closes #474
Closes #475
Closes #476
Closes #477

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[ayomideadeniran]

pr under review