chore: Add tempo-testnet logos

[bizk]

Note

Introduces assets for four ERC-20 tokens on eip155:42431.

• Adds metadata JSON for pathUSD, alphaUSD, betaUSD, thetaUSD (decimals 6, erc20: true) under metadata/eip155:42431/
• Adds corresponding SVG logos under icons/eip155:42431/ and links them via the logo field in each metadata file

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