fix: AI chat loading indicator and auto-refresh tasks

- Add animated typing indicator (bouncing dots) when AI is processing
- Show "Thinking..." status in chat header while processing
- Add translations for AI chat (en/de): title, welcome, placeholder, thinking, error
- Auto-refresh tasks, labels, and user data after AI response
- Disable input field while AI is processing
- Fix translation keys to use ai.chat.* namespace

client/src/i18n/locales/en.json

@@ -440,6 +440,13 @@
       "pullSuccess": "Model pulled successfully",
       "pullError": "Failed to pull model",
       "connectError": "Could not connect to Ollama"
+    },
+    "chat": {
+      "title": "AI Assistant",
+      "welcome": "Hi! I can help you manage tasks, create reminders, and organize your day. Try saying: \"Create a task to buy groceries tomorrow\"",
+      "placeholder": "Ask me anything...",
+      "thinking": "Thinking",
+      "error": "Something went wrong"
     }
   },
   "routines": {