fix: skip tenant association for HasOneThrough ownership relationships - #20506

Description

Fixes #20505.

BelongsToTenant::observeTenancyModelCreation() registers a created observer that returns early for BelongsTo and BelongsToThrough ownership relationships, syncs BelongsToMany, and otherwise calls $relationship->save($tenant). Laravel's HasOneThrough / HasManyThrough are read-only and have no save(), so a resource whose ownership relationship goes through an intermediate model (for example post -> author -> team) crashes on create with:

BadMethodCallException: Call to undefined method Illuminate\Database\Eloquent\Relations\HasOneThrough::save()

This is the tenancy counterpart of #15264 / #15265 (v3), which switched the other relationship checks to the HasOneOrManyThrough base class.

The change adds HasOneOrManyThrough to the early-return guard. The tenant is already implied by the intermediate model, so nothing needs to be written. Query scoping is unaffected because scopeEloquentQueryToTenant() already handles this relationship via whereHas().

Tests:

• tests/src/Panels/Tenancy/HasOneThroughOwnershipTest.php adds a Post::teamThroughAuthor(): HasOneThrough fixture relationship and a resource that uses it for ownership. The first test fails on 4.x with the exception above and passes with this change; the second confirms tenant scoping still filters records through the same relationship.
• Existing tests/src/Panels/Tenancy and tests/src/Panels/Pages/Tenancy suites pass (12 tests).
• phpstan is clean on the trait; composer cs (rector + pint) produced no changes.

The same code exists on 5.x and 6.x.

Visual changes

None.

Functional changes

• Code style has been fixed by running the composer cs command.
• Changes have been tested to not break existing functionality.
• Documentation is up-to-date.