feat: add compare command for side-by-side token comparison (Fixes #23)

[codegraphtheory]

Description

Closes #23 (Bounty: 500,000 $RUG)

Adds solana-rug compare <MINT1> <MINT2> with side-by-side ASCII table output, --json mode, and --sort score|name|age|liquidity.

Acceptance Criteria

• compare command works for 2+ tokens
• ASCII table with Safety Score, Risk Level, Price, Liquidity, Holders, etc.
• Sorted by safety score ascending (riskiest first) by default
• --sort flag for score, name, age, liquidity
• --json flag outputs array
• Error handling: failed token shows ERROR, continues with others
• 3 test cases

Quality Checks

• 35 tests pass, ruff clean
• This PR addresses exactly one issue (Cross-token comparison mode: solana-rug compare #23)

@lb1192176991-lab please post your Solana wallet address for the bounty payment.

[lb1192176991-lab]

Thanks @codegraphtheory! Here is my Solana wallet address for the bounty:

6MZtWYAvneZyAXq4ZKaF3bWPeS99SQ3xjmKp6XwAeh3D