fix: restructure navigationMenuItem type migration for safe upgrade path (#18722)

## Summary

- Restructures the `navigationMenuItem.type` column migration to follow
the established 3-step safe upgrade pattern (used for webhooks, files,
etc.)
- The previous migration added `type` as `NOT NULL DEFAULT 'VIEW'` with
a CHECK constraint in one step, which incorrectly assigned `VIEW` to all
existing rows regardless of their actual type (folders, records, links,
objects)
- Now: (1) migration adds column as nullable, (2) upgrade command
backfills correct type from existing columns (`viewId`,
`targetRecordId`, `targetObjectMetadataId`, `link`) and cleans
conflicting columns, (3) shared utility applies `NOT NULL` + `CHECK`
constraint

### Changes

**Modified:**
- `1773681736596-add-type-to-navigation-menu-item.ts` -- adds column as
nullable, no DEFAULT, no CHECK
- `navigation-menu-item.entity.ts` -- removed `default:
NavigationMenuItemType.VIEW` from column decorator
- `upgrade.command.ts` / `1-19-upgrade-version-command.module.ts` --
wired new command

**Created:**
- `1773681736596-makeNavigationMenuItemTypeNotNull.util.ts` -- shared
utility applying NOT NULL + CHECK constraint
- `1773822077682-make-navigation-menu-item-type-not-null.ts` --
migration calling the util with savepoint (succeeds on fresh installs,
swallows error on upgrades with NULL data)
- `1-19-backfill-navigation-menu-item-type.command.ts` -- upgrade
command that backfills type, cleans conflicting columns, then applies
constraints via the shared utility

### Execution flow

**Existing deployments (upgrade):**
1. TypeORM migration adds nullable `type` column, drops old CHECK
2. Savepoint migration fails gracefully (existing rows have NULL type)
3. 1-18 favorites migration creates items WITH correct type
4. 1-19 backfill command infers type for remaining NULL rows, cleans
conflicting columns, applies NOT NULL + CHECK

**Fresh installs:**
1. TypeORM migration adds nullable `type` column
2. Savepoint migration succeeds immediately (no data, constraints apply
cleanly)

## Test plan

- [x] `npx nx typecheck twenty-server` passes
- [x] `npx nx lint:diff-with-main twenty-server` passes
- [x] `npx nx test twenty-server` passes (477 suites, 4297 tests)
- [ ] Verify fresh database setup with `npx nx database:reset
twenty-server` applies both migrations and constraints correctly
- [ ] Verify upgrade path: existing navigation menu items get correct
type backfilled based on their columns

Made with [Cursor](https://cursor.com)

packages/twenty-server/src/engine/metadata-modules/navigation-menu-item/entities/navigation-menu-item.entity.ts

@@ -39,7 +39,7 @@ import { SyncableEntity } from 'src/engine/workspace-manager/types/syncable-enti
   'CHK_navigation_menu_item_type_fields',
   `("type" = 'FOLDER')
   OR ("type" = 'OBJECT' AND "targetObjectMetadataId" IS NOT NULL)
-  OR ("type" = 'VIEW')
+  OR ("type" = 'VIEW' AND "viewId" IS NOT NULL)
   OR ("type" = 'RECORD' AND "targetRecordId" IS NOT NULL AND "targetObjectMetadataId" IS NOT NULL)
   OR ("type" = 'LINK' AND "link" IS NOT NULL)`,
 )
@@ -87,7 +87,6 @@ export class NavigationMenuItemEntity
     nullable: false,
     type: 'enum',
     enum: NavigationMenuItemType,
-    default: NavigationMenuItemType.VIEW,
   })
   type: NavigationMenuItemType;