fix(examples): correct f_address seed key to postalCode

[os-support-ai]

Fixes #13388

What

examples/app-showcase/src/data/seed/index.ts seeded the field-zoo specimen's
f_address value with postal_code, a key AddressSchema
(packages/spec/src/data/field-value.zod.ts) does not declare — the schema
declares camelCase postalCode. One key, one line:

- f_address: { street: '1 Main St', city: 'Seattle', state: 'WA', postal_code: '98101', country: 'US' },
+ f_address: { street: '1 Main St', city: 'Seattle', state: 'WA', postalCode: '98101', country: 'US' },

No renderer change and no consumer-side alias — the producer (this seed) was
wrong relative to the contract, and the fix is at the producer per AGENTS.md's
contract-first directive.

Evidence

valueSchemaFor({ type: 'address' }, 'stored').safeParse(...) before/after,
built @objectstack/spec dist:

OLD (postal_code): { success: true, data: { street: '1 Main St', city: 'Seattle', state: 'WA', country: 'US' } }
                                                                                    ^ postalCode silently stripped
NEW (postalCode):  { success: true, data: { street: '1 Main St', city: 'Seattle', state: 'WA', postalCode: '98101', country: 'US' } }
                                                                                    ^ retained

Fixture sweep

Repo-wide grep for postal_code, 98101, f_address found no fixture or test
pinning the old (wrong) seed value:

• packages/qa/dogfood/test/field-zoo.matrix.ts asserts its own independent
  f_address write value ({ street: '1 Main', city: 'SF', country: 'US' }),
  unrelated to the seed.
• packages/spec/src/data/analytics-strictness-batchd.test.ts uses AddressSchema
  with its own unrelated fixture ({ street: '1 Main St', district: 'Central' }) —
  part of the separate strictness-fork territory (Two structured value classes (AddressSchema, LocationValueSchema) are all-optional stripping z.objects — a wrong key is accepted and dropped, so a stored-value scan reports a clean count it cannot earn #13802/qa stored-value scans fold strip-mode value classes into a violation count of zero they cannot earn — report them unmeasurable instead #14060), not this seed.
• The other postal_code hits in the tree (company.manifest.ts,
  layout-dsl.mdx, concept.mdx, view.test.ts) are unrelated object field
  names (snake_case machine names on a different object), not this address
  value's key.

No fixture needed updating.

Out of scope (per the card's explicit ⛔s)

• No renderer change in @object-ui/fields.
• No schema change to AddressSchema/LocationValueSchema — the strict-vs-loose
  question is Two structured value classes (AddressSchema, LocationValueSchema) are all-optional stripping z.objects — a wrong key is accepted and dropped, so a stored-value scan reports a clean count it cannot earn #13802 (decision box) and the scan-honesty half is qa stored-value scans fold strip-mode value classes into a violation count of zero they cannot earn — report them unmeasurable instead #14060.

Tests

• pnpm --filter '@objectstack/example-showcase' exec vitest run — 26 test
  files, 364 tests, all passed (includes test/seed.test.ts).
• pnpm --filter '@objectstack/example-showcase' run typecheck — clean.
• pnpm --filter '@objectstack/dogfood' exec vitest run test/field-zoo-roundtrip.dogfood.test.ts test/field-zoo-value-shape.test.ts
  — 2 test files, 91 tests, all passed. This boots the real showcase stack
  (real HTTP round-trip) with the fixed seed — clean boot, showcase_field_zoo
  seeded without error.
• Local gates derived from the diff via node scripts/pm/dispatch-gates.mjs
  (16 matched families) — all green; see the dev report comment on the issue
  for the full list and the one CI-only exception
  (check:dual-build-cjs-loads needs a full-tree pnpm build, which is CI's
  Build Core job).

Changeset

None — examples/app-showcase is "private": true and releases nothing;
skip-changeset label applied per repo convention (pr-automation.yml's
"releases nothing (… examples/ …)" route).

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Generated by Claude Code