refactor(protocol): prune grpc-gateway proto and support go compile

[317787106]

Summary

Closes #6548.

Removes all google.api.http option annotations from gRPC service definitions, deletes eight unused empty proto files under protocol/src/main/protos/core/tron/, and updates option go_package across all proto files to point to the canonical tronprotocol/protocol repository. No RPC method signatures, message types, or service interfaces are changed.

Background

The grpc-gateway project, which relied on google.api.http mappings to translate HTTP requests into gRPC calls, has been deprecated and is no longer maintained. Every gRPC API already has a dedicated HTTP implementation in FullNodeHttpApiService, making the dual HTTP-REST route definitions redundant.

The existing option go_package values pointed to the deprecated grpc-gateway repository (github.com/tronprotocol/grpc-gateway/...). They are updated here to point to the canonical protocol repository (github.com/tronprotocol/protocol/...), which is the correct home for Go code generated from these proto files.

Changes

protocol/src/main/protos/api/api.proto

• Removed google.api.http option blocks from 56 RPC methods across the Wallet, WalletSolidity, WalletExtension, and Monitor services.
• Updated option go_package from github.com/tronprotocol/grpc-gateway/api to github.com/tronprotocol/protocol/api.

Other proto files — go_package updates

File(s)	Old value	New value
api/zksnark.proto	grpc-gateway/api	protocol/api
core/Tron.proto, core/Discover.proto, core/TronInventoryItems.proto	grpc-gateway/core	protocol/core
core/contract/*.proto (12 files)	grpc-gateway/core or absent	protocol/core/contract

Deleted files (protocol/src/main/protos/core/tron/)

Eight empty proto files that served no purpose after grpc-gateway was abandoned:
account.proto, block.proto, delegated_resource.proto, p2p.proto, proposal.proto, transaction.proto, vote.proto, witness.proto

Impact

• gRPC clients (e.g., Trident SDK): no change — all RPC method signatures are identical.
• HTTP clients: all HTTP APIs continue to be served by FullNodeHttpApiService and are unaffected.
• grpc-gateway / HTTP-to-gRPC proxies: the REST route annotations are gone. Anyone still running a custom grpc-gateway setup must migrate to calling gRPC methods directly or use the dedicated HTTP API endpoints.
• Go code generation: option go_package now points to github.com/tronprotocol/protocol. Go consumers should generate stubs from the tronprotocol/protocol repository (a go.mod will be added there to complete Go module support).

Test

NA — this is a pure proto cleanup with no logic changes. The generated Java/gRPC stubs are functionally identical.

[lvs0075]

Why haven’t the go_package entries in Discover.proto and Tron.proto been removed?

[317787106]

Why haven’t the go_package entries in Discover.proto and Tron.proto been removed?

@lvs0075 To support compiling these proto files in Go, update go_package to point to the repository currently in use : github.com/tronprotocol/protocol.

[lvs0075]

approve

[waynercheung]

[SHOULD] This tutorial still tells contributors to set go_package = "github.com/tronprotocol/grpc-gateway/core" (line 22) and to add option (google.api.http) = { ... } to the new RPC (line 56). Both patterns are exactly what this PR removes from the tree, so following the tutorial would re-introduce the deprecated form. Suggest updating both en (lines 22 / 56) and zh (lines 24 / 58):

• go_package → github.com/tronprotocol/protocol/core/contract (matching the new convention used in this PR for *_contract.proto).
• Drop the option (google.api.http) block from the InvokeSum example.

[waynercheung]

[SHOULD] After removing all google.api.http options in this PR, this import has no remaining consumers in the repo (grep -rn "google/api" protocol/ returns only this line). Compilation works either way (it's still provided transitively by proto-google-common-protos), but dropping the import keeps api.proto consistent with the "prune grpc-gateway" goal.