feat(notifications): deduplicate repeated email alerts

Add notification-level deduplication keys and TTLs for deployment, backup,
server, container, scheduled task, SSL, token, and transactional emails.
Apply deduplication in email channels before sending rendered messages.

app/Notifications/Server/DockerCleanupFailed.php

@@ -21,6 +21,16 @@ class DockerCleanupFailed extends CustomEmailNotification
         return $notifiable->getEnabledChannels('docker_cleanup_failure');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "docker-cleanup-failed:server:{$this->server->uuid}:message:".hash('sha256', $this->message);
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 21600;
+    }
+
     public function toMail(): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/DockerCleanupSuccess.php

@@ -21,6 +21,16 @@ class DockerCleanupSuccess extends CustomEmailNotification
         return $notifiable->getEnabledChannels('docker_cleanup_success');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "docker-cleanup-success:server:{$this->server->uuid}:message:".hash('sha256', $this->message);
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 21600;
+    }
+
     public function toMail(): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/ForceDisabled.php

@@ -21,6 +21,16 @@ class ForceDisabled extends CustomEmailNotification
         return $notifiable->getEnabledChannels('server_force_disabled');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "server-force-disabled:{$this->server->uuid}";
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 86400;
+    }
+
     public function toMail(): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/ForceEnabled.php

@@ -21,6 +21,16 @@ class ForceEnabled extends CustomEmailNotification
         return $notifiable->getEnabledChannels('server_force_enabled');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "server-force-enabled:{$this->server->uuid}";
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 86400;
+    }
+
     public function toMail(): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/HetznerDeletionFailed.php

@@ -21,6 +21,16 @@ class HetznerDeletionFailed extends CustomEmailNotification
         return $notifiable->getEnabledChannels('hetzner_deletion_failed');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "hetzner-deletion-failed:{$this->hetznerServerId}:error:".hash('sha256', $this->errorMessage);
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 86400;
+    }
+
     public function toMail(): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/HighDiskUsage.php

@@ -21,6 +21,16 @@ class HighDiskUsage extends CustomEmailNotification
         return $notifiable->getEnabledChannels('server_disk_usage');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "high-disk-usage:server:{$this->server->uuid}:threshold:{$this->server_disk_usage_notification_threshold}";
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 21600;
+    }
+
     public function toMail(): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/Reachable.php

@@ -30,6 +30,16 @@ class Reachable extends CustomEmailNotification
         return $notifiable->getEnabledChannels('server_reachable');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "server-reachable:{$this->server->uuid}";
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 1800;
+    }
+
     public function toMail(): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/ServerPatchCheck.php

@@ -24,6 +24,16 @@ class ServerPatchCheck extends CustomEmailNotification
         return $notifiable->getEnabledChannels('server_patch');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "server-patch-check:server:{$this->server->uuid}:state:".hash('sha256', json_encode($this->patchData));
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 86400;
+    }
+
     public function toMail($notifiable = null): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/TraefikVersionOutdated.php

@@ -38,6 +38,18 @@ class TraefikVersionOutdated extends CustomEmailNotification
         return $this->formatVersion($info['latest'] ?? 'unknown');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        $serverUuids = $this->servers->pluck('uuid')->sort()->values()->join('|');
+
+        return 'traefik-version-outdated:servers:'.hash('sha256', $serverUuids);
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 86400;
+    }
+
     public function toMail($notifiable = null): MailMessage
     {
         $mail = new MailMessage;

app/Notifications/Server/Unreachable.php

@@ -30,6 +30,16 @@ class Unreachable extends CustomEmailNotification
         return $notifiable->getEnabledChannels('server_unreachable');
     }
 
+    public function deduplicationKey(object $notifiable, string $channel): ?string
+    {
+        return "server-unreachable:{$this->server->uuid}";
+    }
+
+    public function deduplicateFor(): int
+    {
+        return 3600;
+    }
+
     public function toMail(): ?MailMessage
     {
         $mail = new MailMessage;