feat(cosmos): replace JSON tx encoding with SDK protobuf via TxConfig and SIGN_MODE_DIRECT

[qj0r9j0vc2]

Summary

• Replace JSON-based transaction encoding with proper Cosmos SDK protobuf encoding
• Use TxConfig for transaction building, encoding, and decoding
• Implement SIGN_MODE_DIRECT for sign bytes generation via authsigning.GetSignBytesAdapter
• Add signature injection using txConfig.WrapTxBuilder for proper tx re-encoding

Changes

• pkg/network/cosmos/txbuilder.go: Refactored BuildTx and SignTx to use SDK's TxBuilder
• pkg/network/cosmos/build_test.go: Added txConfig to test TxBuilder instances
• pkg/network/cosmos/sign_test.go: Updated tests to use real protobuf-encoded bytes
• internal/daemon/controller/transaction.go: Added GasLimit with default 200000
• internal/daemon/types/transaction.go: Added GasLimit field to TransactionSpec
• internal/daemon/server/devnet_service.go: Added RunHooks method
• types/ports.go: Added LabelFilter to DevnetFilter
• internal/application/devnet/export.go: Fixed checksum to use genesis file hash
• cmd/devnet-builder/commands/manage/deploy.go: Added port conflict detection

Test plan

• All cosmos package tests pass (53 tests)
• Full test suite passes for core packages