Support lotus v1.36.0-rc1

[emmanuelm41]

Summary

Bumps Lotus from v1.34.1 → v1.36.0-rc1 (5-version jump, includes new Filecoin Network Version 28).

Changes

• go.mod / go.sum: lotus → v1.36.0-rc1, Go directive 1.23.10 → 1.25.7, transitive churn
• actors/actors.go: LatestVersion bumped network.Version27 → network.Version28
• construction_impl_test.go: 14× t.Errorf(err.Error()) → t.Errorf("%s", err.Error()) (Go 1.25 stricter printf analyzer)
• .github/workflows/main.yml: golang:1.23.10 → golang:1.25.7 in container image and setup-go (×4)

Test plan

• go build ./... clean
• go vet ./... clean
• CI green on this branch
• rosetta-filecoin-proxy PR will reference this branch via go pseudo-version to validate end-to-end before merge
• After both pass: merge here → tag v1.3600.0-rc1 (pre-release) → bump proxy to tagged version → merge proxy → tag proxy

Notes

• _ "github.com/filecoin-project/lotus/build" blank import in actors/actors.go retained (needed since 1.30 modularized build package)
• All 8 specs-actors versions retained; go mod tidy did not prune them