Fix collateral validity check; unify verifier error types; minor comment typos

[tomasandroil]

• Fix: Correct collateral validity window in PCCSRouter._loadDataIfNotExpired to issuedAt <= timestamp <= expiredAt (AND instead of OR).
• Verifiers: Return bytes for error messages in verifyZkOutput (V3/V4) to match function signatures; fix typo in V3 error text.
• Docs: Comment typos fixed (“Succinct”, “ETH”).

Impact

• Prevents accepting expired/not-yet-valid collaterals.
• No storage/layout changes; backwards-compatible interface-wise.

Files

• evm/contracts/PCCSRouter.sol
• evm/contracts/verifiers/V3QuoteVerifier.sol
• evm/contracts/verifiers/V4QuoteVerifier.sol
• evm/contracts/AttestationEntrypointBase.sol
• evm/contracts/bases/FeeManagerBase.sol

Testing

• Built with Foundry; tests executed and passed prior to push.