Fix failing Solidity template tests

[pxlvre]

Issue

Several unit tests are failing in the Solidity template generation:

Failing tests:

• • MultiInheritance contracts not generating expected inheritance chain
• • ERC721 extensions not properly included in contract declaration
• • ERC721 constructor format incorrect
• • Upgradeable contracts still containing constructor code
• • OpenZeppelin dependency installation failing in tests

Root cause:
The template generation logic in lib/src/templates/solidity.rs has issues with:

1. Building proper inheritance chains for MultiInheritance contract types
2. Constructor generation for upgradeable contracts
3. Extension integration for ERC721/ERC1155 contracts

To reproduce:

cargo test templates::solidity::tests::test_multi_inheritance_contract
cargo test templates::solidity::tests::test_erc721_with_extensions  
cargo test templates::solidity::tests::test_upgradeable_contracts

These template bugs affect contract generation quality and need fixing.