fix(showcase): drop dead props f_rating.maxRating / f_vector.vectorConfig (#1973)

The spec-liveness author-warning lint flagged two dead-property usages in
the showcase's field-zoo object that do nothing at runtime:

- f_rating authored `maxRating` (via Field.rating), but RatingField reads
  the flat `max` prop. Author `{ type: 'rating', max: 5 }` directly.
- f_vector authored the nested `vectorConfig` block (via Field.vector), but
  VectorField reads the flat `dimensions` sibling and there is no
  vector-index DDL consuming vectorConfig. Author `{ type: 'vector',
  dimensions: 1536 }` directly.

Switched both from the builder helpers to raw literals (matching the style
of other raw-literal fields in this file) so the showcase authors zero dead
props. `objectstack compile` is clean: exit 0, no liveness-dead-property
warnings, no new errors.

Note: the Field.rating/Field.vector builders themselves still emit the dead
props (field.zod.ts) — a separate follow-up.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: os-zhuang

examples/app-showcase/src/objects/field-zoo.object.ts

@@ -121,13 +121,13 @@ export const FieldZoo = ObjectSchema.create({
     f_code: Field.code('json', { label: 'Code Editor' }),
     f_json: Field.json({ label: 'JSON' }),
     f_color: Field.color({ label: 'Color' }),
-    f_rating: Field.rating(5, { label: 'Rating' }),
+    f_rating: { type: 'rating', label: 'Rating', max: 5 },
     f_slider: Field.slider({ label: 'Slider', min: 0, max: 100, step: 5 }),
     f_signature: Field.signature({ label: 'Signature' }),
     f_qrcode: Field.qrcode({ label: 'QR / Barcode' }),
     f_progress: { type: 'progress', label: 'Progress', min: 0, max: 100 },
 
     // ── AI / ML ──────────────────────────────────────────────────────────
-    f_vector: Field.vector(1536, { label: 'Embedding Vector' }),
+    f_vector: { type: 'vector', label: 'Embedding Vector', dimensions: 1536 },
   },
 });