[Task] Update upgrade notes for 2026.1

Author: jcPimcore

doc/03_Upgrade.md

@@ -2,9 +2,61 @@
 
 ## Upgrade to 2026.1.0
 
+### PHP & Symfony Version Support
+
 - Added support for `PHP` `8.5`.
 - Removed support for `PHP` `8.3` and Symfony `v6`.
-- Changed namespace from `Pimcore\Log\ApplicationLogger` to `Pimcore\Bundle\ApplicationLoggerBundle\ApplicationLogger`
+
+### Removed Admin Classic / ExtJS UI
+
+- Removed `pimcore/admin-ui-classic-bundle` dependency. The bundle no longer implements `PimcoreBundleAdminClassicInterface` or uses `BundleAdminClassicTrait`.
+- Removed all ExtJS-based JavaScript and CSS paths (`getCssPaths()`, `getJsPaths()` methods removed from `PimcoreDataImporterBundle`).
+- `PimcoreAdminBundle` is no longer registered as a dependent bundle.
+- The Admin UI configuration panel is now implemented using the Pimcore Studio UI.
+- `Pimcore\Bundle\AdminBundle\Helper\QueryParams` is no longer used; replaced by `DataTypeServiceInterface::extractSortingSettings()`.
+
+### Studio UI
+
+- Added Studio UI implementation for the Data Importer configuration panel (tabs: Data Setup, Execution, Import Logs).
+- Studio frontend assets are now shipped with the bundle.
+
+### Namespace Changes
+
+- Changed namespace from `Pimcore\Log\ApplicationLogger` to `Pimcore\Bundle\ApplicationLoggerBundle\ApplicationLogger`.
+
+### Messenger Transport Configuration
+
+- The messenger transport DSN is now configurable via the `%pimcore.messenger.transport_dsn_prefix%` container parameter instead of being hardcoded to `doctrine://default`. This allows the installer to wire the transport DSN from environment variables (e.g. `PIMCORE_MESSENGER_TRANSPORT_DSN_PREFIX`).
+
+### Interface & Return Type Changes
+
+- `DataTypeServiceInterface`: Added new method `extractSortingSettings(?string $sort): array` to the interface. Any custom implementations of `DataTypeServiceInterface` must implement this method.
+- `CronValidationResponse::isValid(): bool` renamed to `CronValidationResponse::getIsValid(): bool`.
+- `ImportProgressResponse::isRunning(): bool` renamed to `ImportProgressResponse::getIsRunning(): bool`.
+- `PimcoreDataImporterBundle::getInstaller()` return type changed from `?InstallerInterface` to `InstallerInterface` (non-nullable).
+
+### Class Visibility & Finalization
+
+- Many classes have been marked `final` and/or `@internal`. Custom subclasses of these classes are no longer supported:
+  - `CronScheduler`, `JobScheduler`, `SchedulerFactory` — marked `final` and `@internal`
+  - `PreviewData` — marked `final` and `@internal`
+  - `PimcoreDataImporterBundle` — marked `final`
+  - Various exception classes (`InvalidScheduleException`, etc.) — marked `final`
+- Several `protected` methods on final classes have been changed to `private`. If you were overriding these methods in subclasses, you must refactor.
+- `ConfigDataObjectController::saveAction()` return type changed from `?JsonResponse` to `JsonResponse` (non-nullable).
+- `Installer::getLastMigrationVersionClassName()` return type changed from `?string` to `string` (non-nullable).
+
+### Doctrine
+
+- Removed Doctrine enum mapping from the bundle configuration.
+
+### Dependency Updates
+
+- `phpoffice/phpspreadsheet` version requirement bumped to `^4.3 || ^5.1` (dropped `^2.2 || ^3.3`).
+
+### API Schema Changes
+
+- `UnitDataResponse`: Schema property renamed from `UnitList` to `unitList` (camelCase). If you consume this API response, update your client accordingly.
 
 ## Update to Version 1.11