fix: исправлен синтаксис YAML в Drone CI

- Заменён headers.Content-Type на content_type в webhook настройках
- Исправлена ошибка 'cannot unmarshal !!map into string' на строке 126
- Применено для всех webhook уведомлений (success, failure, deploy)

.drone.yml

@@ -137,8 +137,7 @@ steps:
     settings:
       urls:
         - https://discord.com/api/webhooks/YOUR_WEBHOOK_URL # Замените на ваш webhook
-      headers:
-        Content-Type: application/json
+      content_type: application/json
       template: |
         {
           "content": "✅ **Build Success** - Lottery Bot\n**Branch:** {{build.branch}}\n**Commit:** {{build.commit}}\n**Build:** #{{build.number}}\n**Author:** {{build.author}}"
@@ -156,8 +155,7 @@ steps:
     settings:
       urls:
         - https://discord.com/api/webhooks/YOUR_WEBHOOK_URL # Замените на ваш webhook
-      headers:
-        Content-Type: application/json
+      content_type: application/json
       template: |
         {
           "content": "❌ **Build Failed** - Lottery Bot\n**Branch:** {{build.branch}}\n**Commit:** {{build.commit}}\n**Build:** #{{build.number}}\n**Author:** {{build.author}}\n**Logs:** {{build.link}}"
@@ -237,8 +235,7 @@ steps:
     settings:
       urls:
         - https://discord.com/api/webhooks/YOUR_WEBHOOK_URL # Замените на ваш webhook
-      headers:
-        Content-Type: application/json
+      content_type: application/json
       template: |
         {
           "content": "🚀 **Deployment Complete** - Lottery Bot\n**Environment:** Staging\n**Build:** #{{build.number}}\n**Commit:** {{build.commit}}"