[Breaking change] fix: make pageLayout type field required (#22450)

fixes https://github.com/twentyhq/twenty/issues/22251


**Summary**
- Fixes #22251 — NavigationMenuItem with type PAGE_LAYOUT returns 404
"Off track" for custom standalone pages
- Makes type a required field in PageLayoutManifest instead of relying
on a fallback default to RECORD_PAGE
- Adds PageLayoutType enum to twenty-shared and exports it from the SDK
for app developers
- Adds build-time validation in definePageLayout to reject manifests
missing type
- Updates the CLI add command to prompt users to select a page layout
type interactively

**Root cause**
When definePageLayout was called without type, the manifest converter
defaulted to RECORD_PAGE. The frontend route guard at /page/:id then
rejected it (only STANDALONE_PAGE is allowed), producing a 404.

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packages/twenty-shared/src/application/pageLayoutManifestType.ts

@@ -26,7 +26,7 @@ export type PageLayoutTabManifest = SyncableEntityOptions & {
 
 export type PageLayoutManifest = SyncableEntityOptions & {
   name: string;
-  type?: string;
+  type: string;
   objectUniversalIdentifier?: string;
   defaultTabToFocusOnMobileAndSidePanelUniversalIdentifier?: string;
   tabs?: PageLayoutTabManifest[];