fix(plugins): default AML field references to the new r() syntax

[khaito241]

Problem

When asked to build a dashboard FilterBlock/VizBlock, the skill agent emitted the old field-reference syntax ref('model', 'field') instead of the new r(model.field) syntax (https://docs.holistics.io/release-notes/2025-08-field-ref-validation). ref() still works, but new code should use r(), which the AML compiler statically typechecks.

In references/aml/type_definitions/data_model.aml, Func ref(model_name, field_name) had a full, copyable signature while Func r() {} was an empty stub — so when the agent traced the type defs (FieldFilterSource.field: FieldRef → a defined function), it copied ref(). The dataset example also used ref('...') in its permission blocks, reinforcing it.

Changes

All edits are made in the holistics-common source and propagated to holistics-development / holistics-reporting via pnpm sync-links (those references/ dirs are linked copies — hence the 3× file count).

• data_model.aml — r() is now the documented, canonical builder; ref() is marked legacy. Added a field-kind taxonomy comment covering how to reference each:
  • model dimension/measure → r(model.field)
  • dataset metric → r(dataset.metric)
  • dataset dimension → r(dataset, model.dimension)
  • adhoc calculation (defined in a viz) → bare string 'name', not r()
• dataset.aml — one-line pointers on Type Metric / Type DatasetDimension identifying them as dataset fields and pointing to Func r() for reference syntax.
  • demo_ecommerce.dataset.aml — converted the 3 permission examples from ref('...', '...') to r(...).
  • car_retails.page.aml — added a FilterBlock (the exact construct the agent got wrong) plus a DataTable that demonstrates every reference form (model field, dataset metric, dataset dimension two-arg, and adhoc-calc-as-string), with inline comments.

Verification

• grep -rn "ref('" plugins/ | grep -v "rel_config\|relationship(" → no matches.
• All three plugins' copies are byte-identical (synced from holistics-common).