Move the models.dev data-model types, the provider-id mapping table
(MODELS_DEV_PROVIDER_MAP + mapProviderId), and the raw->OmniRoute transforms
(transformModelsDevToPricing, transformModelsDevToCapabilities) into the pure
leaf src/lib/modelsDevSync/transform.ts (zero imports, no DB, no module state).
modelsDevSync.ts keeps all sync orchestration, DB access, caches and the
periodic-sync timer; it imports the transforms for internal use and re-exports
mapProviderId/transformModelsDevToPricing/transformModelsDevToCapabilities plus
the ModelCapabilityEntry/CapabilitiesByProvider types, so the public API is
unchanged. Host 924->677 LOC; leaf 279 LOC (< 800 cap); host was
frozen-satisfied (934), so this is debt reduction.
238 moved lines are byte-identical. New split-guard test characterizes the
provider map + both transforms and proves the host re-exports them.
