[YaroShkvorets]

Bumps firehose-core from v1.20.1 to v1.21.0.

• firehose-core v1.20.1 → v1.21.0, which also moves bstream to 775b59feeda3 and substreams to v1.25.1-0.20261016154027-d18ca66fe152. gRPC goes to v1.86.0-dev, the version firehose-core v1.21.0 pins.
• go directive: 1.26.0 → 1.27.0. firehose-core v1.21.0 requires Go 1.27.
• The overseer replace already matches firehose-core v1.21.0 (9ebead8ffdef), so it's unchanged.

No code changes were needed. Nothing here uses --firehose-discard-partial-blocks, which v1.21.0 removes.

Checked locally (Go 1.27.2)

• go build, go vet ./... and go test ./... pass
• golangci-lint v2.14.0 (the version CI pins) reports 0 issues. Its release binaries are built with Go 1.27.0, so it accepts the go 1.27.0 directive.

After merge

Tag v0.8.2, then bump local-build eosn-sf-beacon: tag → v0.8.2, version → 1.21.0-0.8.2. Its sf_tag is already v1.21.0, so after that bump firebeacon and firecore use the same firehose-core.

🤖 Made with Claude Code · d97c730a-0b26-4367-8a93-86d376858360

[Copilot]

🔵 Needs a closer look

Upstream compatibility and the new Go toolchain requirement could not be independently verified.

No open issues 🎉

What changed in this PR

Updates the beacon Firehose integration to firehose-core v1.21.0 without application code changes.

Changes:

• Raises the minimum Go version from 1.26.0 to 1.27.0.
• Updates firehose-core, related dependencies, and module checksums.

File	Description
go.sum	Updates checksums for the revised dependency set.
go.mod	Raises the Go requirement and updates dependency versions.

_{Review effort: Balanced}