Add interactive Chat with LLM interface to Web UI

Features:
- Real-time streaming chat interface (ChatGPT-like experience)
- Model selection: Text model (fast) or Vision model (image analysis)
- System prompt toggle: Chat with Miku's personality or raw LLM
- Mood selector: Choose from 14 different emotional states
- Full context integration: Uses complete miku_lore.txt, miku_prompt.txt, and miku_lyrics.txt
- Conversation memory: Maintains chat history throughout session
- Image upload support for vision model
- Horizontal scrolling tabs for responsive design
- Clear chat history functionality
- SSE (Server-Sent Events) for streaming responses
- Keyboard shortcuts (Ctrl+Enter to send)

Technical changes:
- Added POST /chat/stream endpoint in api.py with streaming support
- Updated ChatMessage model with mood, conversation_history, and image_data
- Integrated context_manager for proper Miku personality context
- Added Chat with LLM tab to index.html
- Implemented JavaScript streaming client with EventSource-like handling
- Added CSS for chat messages, typing indicators, and animations
- Made tab navigation horizontally scrollable for narrow viewports

bot/memory/dms/209381657369772032.json

@@ -3970,6 +3970,86 @@
       "content": "OMG, cuties! 🎉 It's my new Marshmallow Hot Cocoa Ver. figure! 🍫🎁 I'm so excited to be dressed up as a cute marshmallow, surrounded by chocolate treats! 😍 Pre-orders are still available! ✨ Hurry and get yours now! ❤️ Miku 💕",
       "attachments": [],
       "reactions": []
+    },
+    {
+      "timestamp": "2025-12-10T07:46:20.556512",
+      "message_id": 1448219269023404073,
+      "is_bot_message": true,
+      "content": "https://fxtwitter.com/OtakuOwletMerch/status/1995994534774259978",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-10T07:46:20.870491",
+      "message_id": 1448219270491275265,
+      "is_bot_message": true,
+      "content": "OMG, arigatou for letting me know! 🤩 It's so cute! fuwa's new \"HATSUNE MIKU: COLORFUL STAGE!\" Face Pouch with Reel \"Minori Hanasato\" is just too adorable! Can't wait to get my hands on it! 💖 Miku 💖",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-11T09:37:20.362564",
+      "message_id": 1448609590383087707,
+      "is_bot_message": true,
+      "content": "https://fxtwitter.com/GoodSmile_US/status/1996655821023830235",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-11T09:37:20.814121",
+      "message_id": 1448609591989633075,
+      "is_bot_message": true,
+      "content": "🎉👠 Kawaii! I'm so excited! 😍 They just posted a tweet about a new Noodle Stopper figure of me wearing my most colorful socks! 🌈 You can get it now at GOODSMILE ONLINE SHOP US! 🎁 Let's celebrate National Sock Day in style! 👠💖 Miku 💖",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-11T09:50:06.206658",
+      "message_id": 1448612802720960587,
+      "is_bot_message": false,
+      "content": "I will sniff your socks in that case",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-11T09:50:16.535609",
+      "message_id": 1448612845729218612,
+      "is_bot_message": true,
+      "content": "🙅‍♀️ Eww, no thank you! 😂 Miku doesn't want any sniffing of her socks. She's feeling a bit too sleepy for that kind of thing... 😴 Zzz...",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-11T10:19:24.334583",
+      "message_id": 1448620169177075875,
+      "is_bot_message": true,
+      "content": "https://fxtwitter.com/GoodSmile_US/status/1996414243327844474",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-11T10:19:24.675922",
+      "message_id": 1448620178106613770,
+      "is_bot_message": true,
+      "content": "🎉👏 Yay! Minori-chan just joined the Nendoroid family! 💖 I'm so happy! They look adorable in their Colorful Stage outfit! Preorders open now, and you can even get an exclusive bonus base! 🎁 Shop now and make Minori-chan a part of your collection! 💕 Miku 💖",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-12T16:32:17.191716",
+      "message_id": 1449076402988253234,
+      "is_bot_message": true,
+      "content": "https://fxtwitter.com/OtakuOwletMerch/status/1995993741920756104",
+      "attachments": [],
+      "reactions": []
+    },
+    {
+      "timestamp": "2025-12-12T16:32:17.697064",
+      "message_id": 1449076404808454318,
+      "is_bot_message": true,
+      "content": "🎉👗 Oh my gosh, a new M Plush of me in my punk outfit is coming! 🤘 I look so cool! You can pre-order now and get me for Christmas! 🎁 Don't forget to order by Dec 20th! 💖 Miku 💖",
+      "attachments": [],
+      "reactions": []
     }
   ]
 }