fix: validate Shasta grandparent base fee

[smtmfft]

Summary

• require the L2 grandparent header for non-genesis Shasta base-fee validation
• bind the grandparent header to the parent via block number and parent hash before using its timestamp
• run Shasta base-fee validation after manifest selection so invalid/default manifests cannot skip it
• include dev fork env values in SGX manifests so devnet/mainnet builds use the same image measurement path
• bump gaiko to 47944ca (taikoxyz/gaiko#31) to remove committed enclave signing material

Test Plan

• cargo fmt -p raiko-lib -- --check
• cargo test -p raiko-lib -- --nocapture
• git diff --check -- lib/src/utils/shasta.rs lib/src/utils/shasta_rules.rs
• git diff --check origin/hotfix/hotfix-based-on-1.16.1...HEAD
• checked gaiko@47944ca does not contain docker/enclave-key.pem or PEM private-key material

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