Restore data feeds restructure changes

[ahermida]

This PR restores the changes from the reverted restructure-data-feeds-docs branch that were previously merged but then reverted due to GitBook compatibility issues.

Changes Included

1. Sample Size Description Update

• Updated the Sample Size field description in the aggregator documentation
• Changed from "number of oracles (samples)" to "number of historical data points (samples)"
• This provides clearer understanding of what the parameter controls

2. HyperEVM (Hyperliquid) Integration Documentation

• Added comprehensive integration guide for Hyperliquid blockchain
• Includes network information (Mainnet Chain ID 999, Testnet Chain ID 998)
• Complete setup instructions and deployment guides
• Code examples for TypeScript/JavaScript integration
• Solidity contract examples for DeFi protocols
• Popular feed hashes for major trading pairs
• Troubleshooting and best practices

Why This PR

The original restructure-data-feeds-docs branch was merged but then reverted because it caused issues with GitBook rendering. This PR recreates those changes on a fresh branch from the current main tip, allowing for:

1. Review and Testing: The changes can be reviewed again to ensure GitBook compatibility
2. Incremental Deployment: Changes can be tested in staging before going live
3. Documentation Completeness: The HyperEVM integration docs are valuable for users

Testing Recommendations

• Test GitBook rendering with these changes
• Verify all links and code examples work correctly
• Check that the new Hyperliquid network information is accurate
• Ensure the Sample Size description change doesn't break existing content

The changes are identical to what was in the original branch, just applied cleanly to the current main branch.