chore: generate v0 JSON RPC specification

[masih]

Consistently generate v0 JSON RPC specification, similar to what's provided for v1 and v2.

Fixes #13153

[Copilot]

Pull Request Overview

This PR adds support for generating the v0 JSON RPC specification alongside existing v1 and v2 outputs.

• Introduces generateOpenRpcGatewayV0 (and V1) calls in gen/docs/main.go
• Extends GetAPIType in api/docgen/docgen.go to recognize the v0 Gateway type
• Records the new chore in CHANGELOG.md

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
gen/docs/main.go	Added calls to generateOpenRpcGatewayV0 and generateOpenRpcGatewayV1 and defined those functions
api/docgen/docgen.go	Added a case "Gateway" branch for v0api.Gateway in GetAPIType
CHANGELOG.md	Logged the chore for generating the v0 JSON RPC specification

Comments suppressed due to low confidence (3)

gen/docs/main.go:21

• There are no tests covering the new v0 spec generator. Consider adding a unit test to verify the generated file at build/openrpc/v0/gateway.json matches expectations.

lets.Go(generateOpenRpcGatewayV0)

api/docgen/docgen.go:524

• The new Gateway branch for v0api is untested. A test should ensure GetAPIType("Gateway", ...) returns the correct interface and reflect.Type for v0.

case "Gateway":

CHANGELOG.md:22

• [nitpick] You may want to update the project README or docs to explain how and where the v0 spec is generated, so consumers know about the new output path.

- chore: generate v0 JSON RPC specification ([filecoin-project/lotus#13155](https://github.com/filecoin-project/lotus/pull/13155))

[rjan90]

LGTM