fix(util): implement diff helper

[andrewtdiz]

Closes #3433

Summary

• Implement util.diff(actual, expected) for string inputs, arrays of strings, and mixed string/string-array inputs.
• Return Node-shaped edit tuples using LCS ordering, including the identical-string [] behavior and common tuple output for identical string arrays.
• Add Node-compatible ERR_INVALID_ARG_TYPE validation for unsupported inputs and non-string array elements.
• Wire the helper through util/sys manifest entries, native namespace enumeration, native dispatch, codegen declarations, and parity gap docs.

Tests

• PATH=/home/github-runner/actions-runner/externals/node24/bin:$PATH ./run_parity_tests.sh --suite node-suite --module util --filter diff
• PATH=/home/github-runner/actions-runner/externals/node24/bin:$PATH ./run_parity_tests.sh --suite node-suite --module util (72/73 passed; existing node-suite/util/get-system-error mismatch remains)
• RUSTC_WRAPPER= cargo check -p perry-runtime -p perry-codegen -p perry-api-manifest -p perry-hir -p perry
• cargo fmt --all -- --check
• git diff --check
• jq empty test-parity/known_failures.json
• ./scripts/check_file_size.sh

[andrewtdiz]

Fixed the API docs drift on this branch.

• Regenerated docs/src/api/reference.md and docs/api/perry.d.ts from the branch-local release binary.
• The refreshed manifest now includes util.diff / sys.diff alongside the current mainline styleText entries.
• Local checks passed: cargo fmt --all -- --check, git diff --check, ./scripts/check_file_size.sh, CARGO_TARGET_DIR=/root/perry/target cargo test -p perry-api-manifest sys_alias_mirrors_util_manifest, RUST_TEST_THREADS=1 CARGO_TARGET_DIR=/root/perry/target cargo test -p perry-runtime util_diff, and CARGO_TARGET_DIR=/root/perry/target cargo test -p perry-hir stable_hash::tests::expr_variant_stable_hash_tags_are_unique.