Cardano Updates

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) from 7.5.6 to 7.6.4.
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/protobufjs-v7.6.4/CHANGELOG.md)
- [Commits](https://github.com/protobufjs/protobuf.js/compare/protobufjs-v7.5.6...protobufjs-v7.6.4)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-version: 7.6.4
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

The validator matches the full H2 heading text against the allowed
section names, so the descriptive title made it an "Unknown section".
Rename the heading to exactly "## Appendix" and point the two incoming
links at #appendix. The descriptive phrasing already lives in the
appendix intro sentence. Addresses rphair's review on PR #1193.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

Bumps [actions/setup-go](https://github.com/actions/setup-go) from 6.0.0 to 6.4.0.
- [Release notes](https://github.com/actions/setup-go/releases)
- [Commits](https://github.com/actions/setup-go/compare/v6...4a3601121dd01d1626a1e23e37211e3254c1c06c)

---
updated-dependencies:
- dependency-name: actions/setup-go
  dependency-version: 6.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Bumps [github.com/blinklabs-io/adder](https://github.com/blinklabs-io/adder) from 0.39.1 to 0.41.0.
- [Release notes](https://github.com/blinklabs-io/adder/releases)
- [Commits](https://github.com/blinklabs-io/adder/compare/v0.39.1...v0.41.0)

---
updated-dependencies:
- dependency-name: github.com/blinklabs-io/adder
  dependency-version: 0.41.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Rename "Appendix A" to "Appendix" (only one appendix, so the letter
violates outline convention and makes anchors fragile), update the two
incoming links to the new anchor, and renumber subsections A.1-A.5 to
1-5 for consistency. Addresses reviewer feedback on PR #1193.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

Add 1.26.x to the go-test matrix and run golangci-lint, nilaway, and the
publish build on 1.26.x so the module is verified on both supported Go
versions (1.25 and 1.26), matching the rest of the Go repos. The module
already requires Go 1.25.

Signed-off-by: Chris Guiney <[email protected]>
Co-authored-by: Claude Opus 4.8 (1M context) <[email protected]>

Go 1.24 is end-of-life. Bump the module's go directive to 1.25.7
(toolchain go1.25.8) and run the golangci-lint and nilaway workflows on
1.26.x, matching the rest of the Go repos.

Signed-off-by: Chris Guiney <[email protected]>
Co-authored-by: Claude Opus 4.8 (1M context) <[email protected]>

Add 1.26.x to the go-test matrix and run golangci-lint, nilaway, and the
publish build on 1.26.x so the module is verified on both supported Go
versions (1.25 and 1.26), matching the rest of the Go repos. The module
already requires Go 1.25.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Signed-off-by: Chris Guiney <[email protected]>

Go 1.24 is end-of-life. Bump the module's go directive to 1.25.7
(toolchain go1.25.8) and run the golangci-lint and nilaway workflows on
1.26.x, matching the rest of the Go repos.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Signed-off-by: Chris Guiney <[email protected]>