test(phpstan): enable PHPStan level 3 for WebServices/

[JohnVillalovos]

Resolve PHPStan level 3 issues found when enabling checking of the WebServices/ directory

[Copilot]

Pull request overview

Enables PHPStan level 3 analysis for WebServices/ by removing it from the staged exclusion list and addressing newly surfaced type/contract issues in several web service controllers and response DTOs.

Changes:

• Include WebServices/ in phpstan_next.neon level 3 analysis by removing its exclusion.
• Normalize several “nullable”/mixed return values to concrete scalars (e.g., 0, '') and tighten some method signatures to satisfy PHPStan.
• Refine response/DTO phpdoc and property typing for collections and ISO datetime fields.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
phpstan_next.neon	Removes staged exclusion so PHPStan level 3 now analyzes WebServices/.
WebServices/SchedulesWebService.php	Adjusts ISchedulePage implementation return values and makes an unimplemented method explicit via exception.
WebServices/Responses/ScheduleResponse.php	Tightens $periods phpdoc to reflect keyed structure.
WebServices/Responses/Resource/ResourceAvailabilityResponse.php	Switches availability timestamps to nullable ISO string properties.
WebServices/Responses/CustomAttributes/CustomAttributeDefinitionResponse.php	Corrects possibleValues typing and simplifies the example payload to valid enum values.
WebServices/Responses/AccessoriesResponse.php	Fixes accessories collection typing and initializes to an empty list.
WebServices/ReservationsWebService.php	Casts query-string IDs to ints/null to satisfy type expectations.
WebServices/Controllers/ReservationSaveController.php	Aligns recurrence interval type with IRepeatOptionsComposite and normalizes missing resourceId to 0.
WebServices/Controllers/GroupSaveController.php	Adds return phpdoc for GetAllowedResourceIds() string format.
WebServices/Controllers/AttributeSaveController.php	Adds parameter/return typing to GetPossibleValues().
Pages/Admin/ManageGroupsPage.php	Updates GetAllowedResourceIds() phpdoc to include string IDs used for permission encoding.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.