chore(types,utils): delete dead ethermint-era helpers

[puneet2019]

Part of the shrink-to-upstream campaign (#309–#316). PR A of the dead-code series from the five-folder symbol-level sweep.

Summary

Deletes 10 dead files (−494 LOC) — 8 Go sources, 1 test, 1 template — orphaned by the rpc/ (#309), in-tree x/evm, and x/erc20 (#221) removals:

File	What it was
types/block.go	BlockGasLimit — rpc-era helper
types/gasmeter.go	ethermint infinite gas meter
types/int.go	SafeInt64/SafeUint64 (the latter added for #292's rpc tests — re-orphaned when #309 deleted them)
types/protocol.go	ProtocolVersion — served the deleted rpc
types/validation.go + test	address validators, test-only and self-referential
types/constant.go	unused DefaultDenom
types/openapiutil/	unreferenced API-console template
utils/eth/eth.go	DeriveChainID/RawSignatureValues — live copies ship in cosmos/evm utils/

Safety

• Symbol-level verification (not package-level): all 17 exported symbols in the deleted files (funcs, types, vars, and consts — incl. IsEmptyHash, IsZeroAddress, ErrorGasOverflow, ErrorNegativeGasConsumed, openapiutil.Handler beyond the originally listed 13) confirmed zero references across the repo — and, per the consumer sweep, across the three known external consumers (moca-storage-provider, moca-go-sdk, moca-challenger).
• The consumer check is what scoped this PR: e.g. types/chain_id.go looks test-only in-repo but ParseChainID is production code in the storage provider's signer — it, grn.go, s3util, resource, common, and the state-critical account.* are untouched.
• go build ./..., go test ./types/... ./utils/..., full test-binary compile sweep (go test -run='^$' ./...), and go vet ./e2e/... (outside CI's unit scope) — green locally and on an amd64 box.

Next in the series: dead client/testnet.go (PR B), two fork-neutral swaps (PR C), dead-symbol trims (PR D).

🤖 Generated with Claude Code

[phenix3443]

I think this should be treated as a breaking Go API change, not just dead-code deletion.

The symbols removed here are exported from the published github.com/mocachain/moca/v2 module surface, for example:

• types.SafeInt64 / SafeUint64 / SafeNewIntFromBigInt / IsValidInt256
• types.ValidateAddress / ValidateNonZeroAddress / IsEmptyHash / IsZeroAddress
• utils/eth.DeriveChainID / RawSignatureValues
• types/openapiutil.Handler

The repo-wide zero-reference check is enough to prove they are dead internally, but it does not prove they are safe to delete for downstream Go consumers. Any external code importing these packages will fail to compile after upgrading to this PR.

If the intent is a non-breaking cleanup, I think these need compat shims / deprecation first. If the intent is to break the module API, that should be called out explicitly as a breaking change rather than a routine chore cleanup.

[puneet2019]

acknowledged, i am ok with breaking changes here