fix(cli): drop stale ownership key from init scaffold object template

The `os init` scaffold emitted `ownership: 'own'` on the starter object
in both the `app` and `plugin` templates. `ownership` is no longer a
valid ObjectSchema field — it's removed from ObjectSchemaBase, and
`ObjectSchema.create()` now rejects unknown top-level keys (ADR-0032 /
#1535). A user copying the scaffolded object into `ObjectSchema.create({...})`
would hit a validation error; the plain-literal form merely hid the
problem while teaching a dead field.

Remove the key from both templates. Rest of the scaffold output is
unchanged; init.test.ts (28 tests) passes and end-to-end render of both
templates confirms no `ownership` remains.

Surfaced during the docs audit in #1866 (getting-started/quick-start.mdx).

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

Author: os-zhuang

packages/cli/src/commands/init.ts

@@ -150,7 +150,6 @@ export default defineStack({
 const ${toCamelCase(namespace)}Item: Data.Object = {
   name: '${namespace}_item',
   label: '${toTitleCase(namespace)} Item',
-  ownership: 'own',
   fields: {
     name: {
       type: 'text',
@@ -223,7 +222,6 @@ export default defineStack({
 const ${toCamelCase(namespace)}Item: Data.Object = {
   name: '${namespace}_item',
   label: '${toTitleCase(namespace)} Item',
-  ownership: 'own',
   fields: {
     name: {
       type: 'text',