fix(model): remove conflicting default on CommodityTariff RandomizationType

[lboue]

Type of change

• 🐛 Fix — corrects a defect or wrong behavior
• ✨ Feature — adds new functionality or capability

Description

CommodityTariff.DayEntryStruct.RandomizationType declared both conformance "[RNDM]" (only allowed
when the Randomization feature is supported) and default: 0. Writing a dayEntries list entry that
omits RandomizationType auto-filled it with that default before validating conformance, then rejected
the very same fill:

Conformance "[RNDM]": Matter does not allow you to set this attribute

This only happens along the list-of-struct write path (Endpoint.setStateOf → supervisor.patch →
StructManager) — a plain state property assignment (agent.get(...).state.dayEntries = [...]) or a
bare, non-list struct attribute with the identical field shape (e.g. CurrentDayEntry) don't trip it.

Per the spec text for both RandomizationOffset and RandomizationType (Application Cluster
Specification § 9.12.5.10.4–5, as transcribed in commodity-tariff.resource.ts): "If this field is not
indicated, randomization shall use the value in the Default* attribute." Absence is spec-meaningful
(fall back to the cluster's own DefaultRandomizationType), not "value is None". RandomizationOffset
already has no default in the model, matching that — RandomizationType's default: 0 was
inconsistent with its sibling field, and collapsed that fallback semantic even when Randomization was
enabled, on top of causing the conformance crash when it wasn't.

Fix: remove the conflicting default: 0.

Backing evidence

• Related issue: CommodityTariff.DayEntryStruct.RandomizationType has both default: 0 and conformance [RNDM], so setStateOf() rejects its own auto-fill #4374
• This fix/change is backed by a complete log file — attached here or in the linked issue (not just a few quoted lines).

(Log attached on #4374, from the real-world crash in a Matterbridge plugin. This PR also adds a
self-contained regression test — CommodityTariffServerTest.ts — that reproduces the exact same error
via MockServerNode + Endpoint.setStateOf(), with and without the fix.)

Checklist

• I understand the code I am submitting and can explain how it works (AI policy)
• Tests added or updated to cover the change
• npm test passes — ran @matter/model's build, @matter/node's full test/behaviors/** suite (390/390, including the new regression test) and @matter/general's suite (1330/1330). Could not complete a full root npm test in this sandbox: the browser/web test step fails on a missing Playwright browser binary, unrelated to this change.
• npm run format-verify and npm run lint pass (both run at the repo root, not just on the touched files)
• CHANGELOG updated

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[Apollon77]

nooo, we never change the model files directly!

And in fact the default: "None" is basically defined by spec ... so have you more details like exact code to check that and verify? But the fix - if we change the default at all is a model override but this more looks like some other root cause. I close this PR and will check the issue later