fix(pegboard): unpack global runner config keys correctly

[NathanFlurry]

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[NathanFlurry]

• fix(pegboard): isolate runner config dc lookup failures #4625 : 2 dependent PRs (#4626 , #4630 )
• docs(pegboard): note runner config upsert split write risk #4624
• fix(pegboard): unpack global runner config keys correctly #4623 👈 (View in Graphite)
• fix(pegboard-gateway): enforce tunnel message state #4622
• fix(pegboard-runner): clear terminal tunnel routes #4621
• fix(pegboard): skip protocol version keys in runner pool backfill #4620
• fix(pegboard): create missing normal runner configs #4619
• fix(epoxy): reuse cached optimistic value #4618
• main

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[claude]

PR Review: fix(pegboard): unpack global runner config keys correctly

Summary: Minimal, targeted bug fix correcting a mismatch between TuplePack and TupleUnpack for GlobalDataKey.

Root Cause

In GlobalDataKey::TuplePack, the key is packed with 7 tuple elements: RUNNER, CONFIG, GLOBAL, DATA, dc_label, namespace_id, name. The old TupleUnpack only consumed 6 elements, skipping DATA. This would silently corrupt key parsing: DATA (value 4, stored as usize) would be misread as dc_label (a u16), and all downstream fields would shift incorrectly.

Fix

Adds the missing usize for DATA to align unpack with pack. Correct and minimal.

Verification Against Peer Keys

Cross-checked all other key types in the file against their pack/unpack tuple arity:

• DataKey: pack 5 elements, unpack 5 elements (correct)
• ByVariantKey: pack 6 elements, unpack 6 elements (correct)
• ProtocolVersionKey: pack 6 elements, unpack 6 elements (correct)
• GlobalDataKey after fix: pack 7 elements, unpack 7 elements (correct)

Notes

• No test coverage added (checklist item unchecked). A round-trip test packing and unpacking a GlobalDataKey and asserting field equality would guard against future regressions of this class of bug.
• The mismatch would only surface at runtime when a GlobalDataKey is read back from the database, making it a latent data corruption issue rather than an immediately visible compile-time failure.

Overall: LGTM. The fix is clearly correct.