web/seo: Änderungsdatum unabhängig von Aufrufen, EN-URLs in Sitemap und Legacy-API, signierte Bounce-Referenz, Merge/Canonical konsistent (Umsetzungsaudit 29.09.: R-02 bis R-11, N17, N18, OPT-1, OPT-2; 02.10.: O01)

- R-02/K-03: Aufrufaggregation und Merge ändern updated_at nicht mehr; neue
  Spalte press_releases.content_changed_at (INSTANT), contentModifiedAt()
  für Sitemap-lastmod, dateModified und article:modified_time
- R-03: Sitemap und Legacy-view_url mit /en/ für englische Meldungen
- R-04/O01: X-Pk-Ref je Empfänger per HMAC signiert; auf eine Sperre zählt —
  hart wie weich — nur ein gültig signierter Rückläufer, unsignierte
  standardmäßig nur zur Sichtung (BOUNCE_UNSIGNED_KIND=policy)
- R-05/R-06: Unmerge setzt nur unveränderte Füllwerte zurück
  (company_merge_moves.merged_value), Canonical-Neubewertung nach Merge und
  Unmerge, assignAll setzt veraltete Verweise zurück
- R-07 bis R-11: Crawler zählen nicht als Aufruf, Mail-Klick gedrosselt und
  verzögert geschrieben, Claim-Zähler erst nach Versand, email_bounces nach
  395 Tagen gelöscht, Canonical-Portal über Kategorie-ID, llms-Cache geleert,
  Feed-Teaser ohne Doppel-Escaping, Merge-Ketten aufgelöst
- N17/N18: kein falsches „gelistet seit", Rollen im Indexbericht wie Sitemap
- OPT-1/OPT-2: topFeeds in SQL, purge-events löscht nach Grenz-ID

Enthält aus PressRelease.php auch die Card-Bild-Helfer (B-01) und
wasEverPublished()/neverPublished() (A-05), weil die Datei ungeteilt
committet ist.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/Feature/CompanyMergeTest.php

@@ -3,6 +3,7 @@
 use App\Enums\CompanyAddressClass;
 use App\Enums\CompanyMergeSubject;
 use App\Enums\Portal;
+use App\Models\Category;
 use App\Models\Company;
 use App\Models\CompanyEmailGroup;
 use App\Models\CompanyMerge;
@@ -12,6 +13,7 @@ use App\Models\User;
 use App\Services\Company\CompanyMergePlan;
 use App\Services\Company\CompanyMergeService;
 use App\Services\Company\CompanyMergeSkip;
+use App\Services\Company\MergedNewsroomLookup;
 use Illuminate\Support\Facades\Artisan;
 use Illuminate\Support\Facades\DB;
 use Tests\TestCase;
@@ -345,3 +347,118 @@ test('the merge list shows survivor, merged companies and the URLs to check', fu
         ->expectsOutputToContain('muster-gmbh')
         ->assertSuccessful();
 });
+
+test('merge and unmerge leave updated_at of the moved releases untouched', function () {
+    /** @var TestCase $this */
+    mergeGroup('info@muster.de');
+    mergeMember('info@muster.de', Portal::Presseecho, 3);
+    $loser = mergeMember('info@muster.de', Portal::Businessportal24, 1);
+    $release = PressRelease::withoutGlobalScopes()->where('company_id', $loser->id)->sole();
+    $before = $release->updated_at->toDateTimeString();
+
+    $this->travel(3)->days();
+    $service = app(CompanyMergeService::class);
+    $merge = $service->merge(planFor('info@muster.de'), 'b');
+    expect(PressRelease::withoutGlobalScopes()->find($release->id)->updated_at->toDateTimeString())->toBe($before);
+
+    $service->revert($merge);
+    expect(PressRelease::withoutGlobalScopes()->find($release->id))
+        ->company_id->toBe($loser->id)
+        ->updated_at->toDateTimeString()->toBe($before);
+});
+
+test('unmerge keeps a field the customer changed after the merge', function () {
+    /** @var TestCase $this */
+    mergeGroup('info@muster.de');
+    $survivor = mergeMember('info@muster.de', Portal::Presseecho, 3, ['website' => null, 'boilerplate' => null, 'phone' => null]);
+    mergeMember('info@muster.de', Portal::Businessportal24, 0, ['website' => 'https://muster.de', 'boilerplate' => 'Über Muster', 'phone' => '030 2']);
+
+    $service = app(CompanyMergeService::class);
+    $merge = $service->merge(planFor('info@muster.de'), 'b');
+
+    expect($merge->moves()->where('field', 'boilerplate')->value('merged_value'))->toBe('Über Muster');
+
+    // Der Kunde beansprucht den Newsroom und schreibt den Text neu.
+    $survivor->refresh()->update(['boilerplate' => 'Unser eigener Text']);
+
+    $service->revert($merge);
+    $survivor->refresh();
+
+    expect($survivor->boilerplate)->toBe('Unser eigener Text')
+        ->and($survivor->website)->toBeNull()
+        ->and($survivor->phone)->toBeNull();
+});
+
+test('unmerge of an older merge without stored fill value compares against the merged company', function () {
+    /** @var TestCase $this */
+    mergeGroup('info@muster.de');
+    $survivor = mergeMember('info@muster.de', Portal::Presseecho, 3, ['website' => null, 'boilerplate' => null]);
+    mergeMember('info@muster.de', Portal::Businessportal24, 0, ['website' => 'https://muster.de', 'boilerplate' => 'Über Muster']);
+
+    $service = app(CompanyMergeService::class);
+    $merge = $service->merge(planFor('info@muster.de'), 'b');
+    // Stand vor der Migration: kein Füllwert in der Move-Zeile.
+    $merge->moves()->update(['merged_value' => null]);
+
+    $survivor->refresh()->update(['boilerplate' => 'Unser eigener Text']);
+    $service->revert($merge);
+    $survivor->refresh();
+
+    expect($survivor->boilerplate)->toBe('Unser eigener Text')
+        ->and($survivor->website)->toBeNull();
+});
+
+test('merge and unmerge re-evaluate the canonical assignment of the moved releases', function () {
+    /** @var TestCase $this */
+    config()->set('canonical.enabled', true);
+    config()->set('canonical.portal_by_category', ['it' => 'businessportal24']);
+
+    $category = Category::factory()->create(['portal' => Portal::Both]);
+    $category->translations()->create(['locale' => 'de', 'name' => 'IT', 'slug' => 'it']);
+
+    mergeGroup('info@muster.de');
+    $survivor = mergeMember('info@muster.de', Portal::Businessportal24, 2);
+    $loser = mergeMember('info@muster.de', Portal::Presseecho);
+
+    $source = PressRelease::factory()->published()->forPortal(Portal::Businessportal24)->for($category)
+        ->create(['company_id' => $survivor->id, 'title' => 'Neuer Standort', 'text' => '<p>Gleicher Text</p>']);
+    $copy = PressRelease::factory()->published()->forPortal(Portal::Presseecho)->for($category)
+        ->create(['company_id' => $loser->id, 'title' => 'Neuer Standort', 'text' => '<p>Gleicher Text</p>']);
+
+    // Verschiedene Firmen: kein Paar.
+    expect($copy->fresh()->canonical_press_release_id)->toBeNull();
+
+    $service = app(CompanyMergeService::class);
+    $merge = $service->merge(planFor('info@muster.de'), 'b');
+
+    expect($copy->fresh()->canonical_press_release_id)->toBe($source->id)
+        ->and($source->fresh()->canonical_press_release_id)->toBeNull();
+
+    $service->revert($merge);
+
+    // Wieder verschiedene Firmen: der Verweis auf die fremde Meldung fällt.
+    expect($copy->fresh()->canonical_press_release_id)->toBeNull()
+        ->and($source->fresh()->canonical_press_release_id)->toBeNull();
+});
+
+test('an old newsroom slug follows a chain of merges to the current survivor', function () {
+    /** @var TestCase $this */
+    mergeGroup('info@muster.de');
+    $middle = mergeMember('info@muster.de', Portal::Presseecho, 2, ['slug' => 'muster-mitte']);
+    mergeMember('info@muster.de', Portal::Presseecho, 1, ['slug' => 'muster-alt']);
+
+    $service = app(CompanyMergeService::class);
+    $service->merge(planFor('info@muster.de'), 'b1');
+
+    // Später: Die Mitte geht ihrerseits in einer weiteren Firma auf.
+    $final = mergeMember('info@muster.de', Portal::Presseecho, 5, ['slug' => 'muster-neu']);
+    PressRelease::withoutGlobalScopes()->where('company_id', $final->id)->update(['published_at' => now()->subDay()]);
+    $service->merge(planFor('info@muster.de'), 'b2');
+
+    expect(Company::withTrashed()->find($middle->id)->trashed())->toBeTrue()
+        ->and(app(MergedNewsroomLookup::class)->survivorFor(['presseecho', 'both'], 'muster-alt')?->id)->toBe($final->id);
+
+    $this->get('https://presseecho.test/de/newsroom/muster-alt')
+        ->assertRedirect('https://presseecho.test/de/newsroom/muster-neu')
+        ->assertStatus(301);
+});