feat: find starting block number by binary search (SS2-88)

[BaoHG1508]

Description of change

• Made startingBlockNumber optional in IndexerConfig
• Added findContractDeploymentBlock() utility using binary search with starknet_getNonce
• Updated indexer to resolve the starting block from contract addresses when startingBlockNumber is not provided
• Finds the earliest deployment block across all configured contracts
• Added logging and performance timing for deployment block resolution

Issue number

Closes #44

Type of change (delete irrelevant types)

• New feature (non-breaking change which adds functionality)

Checklist:

• I have tested locally and linked a screen recording with this PR
• I have adhered to clean code conventions
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works

[metalboyrick]

make CI pass