feat(infra): add SearXNG dev container

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

searxng/settings.yml

@@ -0,0 +1,15 @@
+use_default_settings: true
+server:
+  secret_key: 'dev-secret-change-in-prod'
+  limiter: false
+  image_proxy: false
+  default_http_headers:
+    X-Content-Type-Options: nosniff
+    X-Download-Options: noopen
+    X-Robots-Tag: noindex, nofollow
+search:
+  formats:
+    - html
+    - json
+ui:
+  default_locale: de