feat(settings): add Skills toggle for Codex CLI and improve config editor UX

Add "Enable Skills" toggle below "Enable WebSocket" in Codex CLI settings,
writing `skills = true` under [features] in config.toml. Also add max-height
to auth.json and config.toml textareas, and fix TOML section key insertion
to avoid stray blank lines between entries.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/i18n/messages/de.json

@@ -515,6 +515,8 @@
       "selectReasoningEffort": "Reasoning Effort auswählen",
       "enableWebsocket": "WebSocket aktivieren",
       "enableWebsocketAria": "WebSocket für Codex Provider aktivieren",
+      "enableSkills": "Skills aktivieren",
+      "enableSkillsAria": "Skills für Codex aktivieren",
       "authJsonNative": "auth.json (nativ)",
       "configTomlNative": "config.toml (nativ)"
     },