[4.x] Add more relation type annotations (#1424)

This pull request adds improved PHPDoc type annotations to several
Eloquent relationship methods, enhancing static analysis and developer
experience. These changes clarify the expected return types for
relationships, making the codebase easier to understand and work with.

Relationship method type annotations:

* Added a detailed return type annotation to the `tenant` method in the
`BelongsToTenant` trait, specifying the related model and the current
class.
* Added a detailed return type annotation to the `domains` method in the
`HasDomains` trait, specifying the related model and the current class.
* Added a detailed return type annotation to the `tenants` method in the
`ResourceSyncing` class, specifying the related model and the current
class.

src/Database/Concerns/BelongsToTenant.php

@@ -17,6 +17,9 @@ trait BelongsToTenant
 {
     use FillsCurrentTenant;
 
+    /**
+     * @return BelongsTo<\Illuminate\Database\Eloquent\Model&\Stancl\Tenancy\Contracts\Tenant, $this>
+     */
     public function tenant(): BelongsTo
     {
         return $this->belongsTo(config('tenancy.models.tenant'), Tenancy::tenantKeyColumn());

src/Database/Concerns/HasDomains.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace Stancl\Tenancy\Database\Concerns;
 
+use Illuminate\Database\Eloquent\Relations\HasMany;
 use Stancl\Tenancy\Contracts\Domain;
 use Stancl\Tenancy\Tenancy;
 
@@ -14,7 +15,10 @@ use Stancl\Tenancy\Tenancy;
  */
 trait HasDomains
 {
-    public function domains()
+    /**
+     * @return HasMany<\Illuminate\Database\Eloquent\Model&\Stancl\Tenancy\Contracts\Domain, $this>
+     */
+    public function domains(): HasMany
     {
         return $this->hasMany(config('tenancy.models.domain'), Tenancy::tenantKeyColumn());
     }

src/ResourceSyncing/ResourceSyncing.php

@@ -105,6 +105,9 @@ trait ResourceSyncing
         return true;
     }
 
+    /**
+     * @return BelongsToMany<\Illuminate\Database\Eloquent\Model&\Stancl\Tenancy\Database\Contracts\TenantWithDatabase, $this>
+     */
     public function tenants(): BelongsToMany
     {
         return $this->morphToMany(config('tenancy.models.tenant'), 'tenant_resources', 'tenant_resources', 'resource_global_id', 'tenant_id', $this->getGlobalIdentifierKeyName())