ci: standardize plugin automation

[carlosflorencio]

Summary

• add PR verification and package-build workflows using the sibling Kandev SDK layout
• align tag releases with verification, manifest/tag version checks, and extracted package checksums
• document automated checks and release assets

Validation

• go mod tidy with no remaining module diff
• formatting, vet, and tests
• host and five-platform package builds
• workflow linting with actionlint

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Summary by cubic

Standardizes plugin CI/CD with sibling kdlbs/kandev SDK layout. Adds PR verify/build workflows and tightens releases to match manifest.yaml version and publish internal checksums.

• New Features

  • Added PR CI workflow: go mod tidy check, format, vet, and tests using a sibling kdlbs/kandev checkout.
  • Added PR Build workflow: host build and 5‑platform packaging.
  • Updated release workflow: verifies tag equals manifest version, re-runs verification, packages all platforms, and uploads the tarball plus extracted internal checksums.txt via softprops/action-gh-release@v2.

• Dependencies

  • Bumped golang.org/x/net to v0.55.0, golang.org/x/sys to v0.45.0, and google.golang.org/grpc to v1.82.1.

^{Written for commit 542f331. Summary will update on new commits.}