[rolfyone]

Schedules the Glamsterdam upgrade (Gloas) on Sepolia, following
eth-clients/sepolia#126.

• GLOAS_FORK_VERSION: 0x90000076
• GLOAS_FORK_EPOCH: 353024 (timestamp 1791294816, October 6 2026 13:53:36 UTC)
• Adds the Gloas consensus config values: builder withdrawal delay, attestation/ aggregate/sync-committee/contribution/payload/payload-attestation due-BPS timings, churn limits, and MAX_REQUEST_PAYLOADS.

Values match Teku's existing mainnet.yaml Gloas defaults, scaled to Sepolia's
fork version and epoch. Execution-layer-only fields from the upstream PR
(Besu amsterdamTime, Nethermind EIP transition timestamps) don't apply here
since Teku is a consensus client.

fixes #11306

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

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Note

Medium Risk
Network fork scheduling and new consensus timing/churn parameters affect Sepolia behavior at activation; misconfiguration could cause client divergence from other implementations.

Overview
Schedules the Glamsterdam (Gloas) hard fork on Sepolia at epoch 353024 (October 6, 2026), with fork version 0x90000076, aligned with eth-clients/sepolia#126.

sepolia.yaml gains the Gloas fork activation plus the associated consensus parameters (builder withdrawability delay, Gloas-specific attestation/aggregate/sync/contribution/payload timing BPS values, churn and consolidation limits, and MAX_REQUEST_PAYLOADS), using the same numeric defaults as Teku’s mainnet Gloas preset. The changelog records the scheduled activation.

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