fix: amino JSON signing for MsgSetRoutingIsmDomain

[rootulp]

Closes #156

Summary

• Fix Amino JSON signing bug where multisig transactions containing MsgSetRoutingIsmDomain fail with "unknown protobuf field" for the nested Route message
• Add proto_init.go to register types.proto before tx.proto, ensuring Route resolves correctly
• Add a regression test that verifies GetSignBytes succeeds for MsgSetRoutingIsmDomain

Root Cause

Go runs init() functions in alphabetical file order. Since tx.pb.go sorts before types.pb.go ('x' < 'y'), tx.proto's file descriptor was registered first. tx.proto references the Route message from types.proto, but types.proto wasn't in the registry yet, so Route became a placeholder with 0 fields. RejectUnknownFields used this broken placeholder and rejected all Route fields as unknown.

Fix

proto_init.go sorts before tx.pb.go ('p' < 't') and registers types.proto early. When tx.pb.go's init() subsequently processes tx.proto, Route resolves correctly from the registry with its 2 fields.

Context

See celestia-app#6541 for the original report. This blocked Celestia's multisig signers from submitting MsgSetRoutingIsmDomain transactions.

Test plan

• go test ./x/core/01_interchain_security/types/ -run TestAminoJSONSigningMsgSetRoutingIsmDomain -v passes
• All 28 existing specs in the package still pass

🤖 Generated with Claude Code

[rootulp]

IMO this was super hacky so I researched two alternatives:

1. Rename types.proto to something that sorts before tx.proto — e.g. models.proto or domain.proto ('d' < 't', 'm' < 't'). This would fix the ordering naturally but requires regenerating all protobuf code and updating all import paths.
2. Move Route into tx.proto — eliminates the cross-file dependency entirely, but scatters the data model.

[rootulp]

The same bug is likely also occurring for warp tx.proto and types.proto because tx.proto imports RemoteRouter which is defined in types.proto but that will be registered after tx.proto.

MsgEnrollRemoteRouter and MsgRemoteTransfer likely can't be signed by multisigs via Amino either.

[rootulp]

TBH I think this implementation is hacky and doesn't resolve it for all modules. Going to opt for

Rename types.proto to something that sorts before tx.proto — e.g. models.proto or domain.proto ('d' < 't', 'm' < 't'). This would fix the ordering naturally but requires regenerating all protobuf code and updating all import paths.

[rootulp]

We should probably do the proto init thing for x/warp too.

[rootulp]

Updated the PR title. This PR actually fixes amino JSON signing for multiple messages but that would be a long PR title.

[rootulp]

I just read the contributor guidelines and this prob deserves a CHANGELOG.

[mbreithecker]

Hey, this deserves a Changelog, but will add this later.

[rootulp]

I added a changelog in a787d3a