Form-view FormField.visibleOn (CEL) is never evaluated — conditional fields always render #2212

Symptom

A form view section field with a CEL `visibleOn` predicate is always visible. Showcase repro (framework `examples/app-showcase/src/views/task.view.ts`):

```ts
{ field: 'notes', visibleOn: Precord.priority == 'urgent', colSpan: 2 }
```

The server meta correctly ships `"visibleOn": {"dialect":"cel","source":"record.priority == 'urgent'"}` (verified via `GET /api/v1/meta/view/showcase_task` → `.formViews.default.sections[0].fields[6]`), but the notes field renders even when priority = Low. Field-level `visibleWhen`/`readonlyWhen`/`requiredWhen` all work — only the view-level `FormField.visibleOn` is dead.

Root cause — the chain is broken in three places

Console edit path: `AppContent` → `ModalForm` (+ `resolveFormViewLayout` sections) → `buildSectionFields` (`packages/plugin-form/src/sectionFields.ts`) → SchemaRenderer `type:'form'` → `packages/components/src/renderers/form/form.tsx`.

1. Object shape silently dropped — `sectionFields.ts` `attachVisibility()` (line 45) and `ObjectForm.tsx` `normalizeVisibility()` (line 411) only accept `typeof expr === 'string'`. The spec `P`-template wire shape is `{dialect:'cel', source}` → predicate never attached.
2. The evaluator isn't CEL — even for a string expr, the attached `visible(formData)` calls `evaluateCondition()` (`packages/fields/src/index.tsx:1833`), which only understands legacy `{field, operator, value}` objects and returns `true` for any unknown format ("Default to true").
3. Nothing consumes the predicate anyway — no renderer in the form chain ever calls `FormField.visible(formData)`; `form.tsx:538` destructures `visibleOn` out of the field config and drops it on the floor.

Meanwhile the working field-level rules go through the canonical engine: `resolveFieldRuleState`/`evalFieldPredicate` (`packages/core/src/evaluator/fieldRules.ts`), which already accepts `string | {dialect, source}` and binds `record` scope via `@objectstack/formula` ExpressionEngine (ADR-0036: no private expression DSL).

Fix direction

Route view-level `FormField.visibleOn` through the same canonical engine:

• `form.tsx`: evaluate `visibleOn` with `evalFieldPredicate` against the live `ruleRecord` (fail-open), both at field render and in the stale-error-clearing effect.
• `sectionFields.ts`: carry `visibleOn` (string or `{dialect, source}`) through `normalizeSectionField` instead of attaching a dead `visible()` closure; also carry field-level `visibleWhen`/`readonlyWhen`/`requiredWhen` from object-schema metadata so sectioned forms honor them like flat forms do.
• `types/form.ts`: widen `FormField.visibleOn` to the spec Expression shape.

Found while dogfooding the framework app-showcase (list/form capability audit, P0-16).