docs(spec): regenerate field reference for the readonly INSERT-strip describe (#3043)

`content/docs/references/data/field.mdx` is generated from the spec Zod
`describe()` strings; the `readonly` describe changed in this PR, so the
`check:docs` gate (run under the "TypeScript Type Check" job) flagged it as
drifted. Regenerated via `gen:schema && gen:docs` — no hand edits.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P5fRY4ctobCeFpBba1oGrz

Author: claude

content/docs/references/data/field.mdx

@@ -150,7 +150,7 @@ const result = Address.parse(data);
 | **conditionalRequired** | `string \| { dialect: Enum<'cel' \| 'js' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Predicate (CEL) — field is required when TRUE. Alias of `requiredWhen`. |
 | **widget** | `string` | optional | Form widget override — names a registered field component (resolved as `field:<widget>`) to render this field instead of the `type` default. Degrades to the `type` renderer when unregistered. e.g. "object-ref", "filter-condition", "recipient-picker". |
 | **hidden** | `boolean` | optional | Hidden from default UI |
-| **readonly** | `boolean` | optional | Read-only — never editable in forms, AND server-enforced on UPDATE: a non-system write to this field is silently dropped from the payload (#2948/#3003; symmetric with `readonlyWhen`). INSERT may still seed it (defaultValue, import). |
+| **readonly** | `boolean` | optional | Read-only — never editable in forms, AND server-enforced on BOTH write paths: a non-system write to this field is silently dropped from the payload on UPDATE (#2948/#3003) and on INSERT (#3043; a create can no longer directly seed e.g. `approval_status: "approved"`), symmetric with `readonlyWhen`. A stripped INSERT field still falls back to its `defaultValue`; system-context writes (import, seed replay, migration) are exempt. |
 | **requiredPermissions** | `string[]` | optional | [ADR-0066 D3] Capabilities required to read/edit this field (mask on read, deny on write; AND-gate). |
 | **system** | `boolean` | optional | Auto-injected system/audit field (e.g. created_at, updated_by, organization_id). Tools that surface system fields separately from author-declared business fields should branch on this flag. |
 | **sortable** | `boolean` | optional | Whether field is sortable in list views |