PROD-1492: halt sync on model/template mapping-validation errors

[jules-exel]

Summary

Promobanner duplicate issue was not able to be replicated, it was most likely caused by stale mappings, however the errors thrown now stop the sync for these two issues.

The old fix checked "is this one model's ID inconsistent with its mapping?" (a per-model, ID-based rename check). The code never ever checked "does the mapping file contain two records with the same reference name?" Both issues have been addressed and waiting review.

Two related fixes so a mapping-inconsistency guard actually stops the sync for the PROD-1492 scenario, instead of being swallowed and silently continuing into a partial push.

1. Template validation error was swallowed

The guid-level orchestrator only re-threw errors whose message contained "Model validation failed". The template guard throws "Page template validation failed", which didn't match — so it fell through to a yellow Warning during guid-level operations and the sync kept going (the LeftSideBarTemplate mapping-inconsistency case).

Fix: broaden the re-throw match in orchestrate-pushers.ts to any "validation failed", so the template guard — and any future validation guard — hard-stops the sync.

2. Duplicate model reference-name was never detected

When a source model is deleted and recreated (new ID, same referenceName), the mapping keeps two records sharing that name — one pointing at the dead source model, one at the live one. The content-side lookup (getModelMappingByReferenceName) is first-match-wins, so it can latch onto the dead record, fail to read its (deleted) source model, and silently skip that model's content — after which every page referencing it fails with No content mapping. The existing ID-based rename guard misses this because the two records have different source IDs (a duplicate name, not a duplicate ID).

Fix: add ModelMapper.getDuplicateSourceReferenceNames() and a pre-push integrity gate in pushModels that throws Model validation failed: duplicate model mapping ... before any writes. Because the message contains "validation failed", fix #1 ensures the orchestrator halts on it.

Tests

• orchestrate-pushers.test.ts — a template-validation failure aborts the sync before content/pages are pushed.
• model-pusher.test.ts — a duplicate-reference-name mapping throws Model validation failed and writes nothing (seeded with the real PromoBanner 46→138 / 48→139 shape).
• Added per-test mapping-file cleanup in model-pusher.test.ts so seeded mappings no longer leak between tests.

Before error showing and sync continuing:

After error showing sync now stops: