Fix native build issues and modernize GitHub Actions workflows

[NINJAK1DD]

Summary

This PR fixes native build issues affecting CI and updates GitHub Actions workflow versions.

Changes included

• fixed missing integer type headers in native code
• adjusted native build handling for RandomARQ and Panthera-related build failures
• updated GitHub Actions workflow actions to current supported versions
• cleaned up CI so the workflow runs more reliably on GitHub-hosted runners

Why

The existing CI pipeline was failing during native library builds and some workflow actions were using older versions. This PR brings the build pipeline back into a working state and modernizes the workflow definitions.

Validation

• branch pushed successfully
• pull request created against dev
• GitHub Actions checks to be used as validation for the updated workflow and native build fixes

Risk

Low to moderate. Changes affect native build and CI workflow behavior, so the main risk area is build/runtime compatibility.

Rollback

Revert this PR if CI or native builds regress after merge.

[NINJAK1DD]

This PR is intentionally limited to:

• native include/build fixes
• GitHub Actions modernization

The remaining failing checks are pre-existing and reproduce on dev itself.

I verified this locally with:

dotnet test src --filter "FullyQualifiedName~CoinTemplateValidationTest|FullyQualifiedName~BitcoinJobTests"

The same failures occur on dev:

• CoinTemplateValidationTest due to coins.json referencing x11kvs while only x11 is registered
• BitcoinJobTests failing with low difficulty share (...)

I will open a separate follow-up branch/PR for those repo-level test fixes so this PR stays focused.

[NINJAK1DD]

Merging this despite red CI because the current failures are expected and unrelated to this PR’s scope:

• missing hasher registrations are handled in PR Restore missing hash algorithm registrations and native exports #14
• stale Bitcoin/Lyra test issues will be handled in the separate stale test PR
  This PR is only for workflow/native include fixes.