Add weather caching, useless-tip redirect, clock widget, and IAM Bedrock auth

- Cache the latest fetched tomorrow weather and expose it via /api/system/weather/latest
- Add a header Clock widget showing date/time plus the cached weather summary
- Redirect useless-talk mentions from the weather bot to the useless-tips webhook
- Switch Bedrock auth from bearer token to standard IAM access key/secret

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/core/discord_bot.py

@@ -11,7 +11,9 @@ from app.core.config import (
     WEATHER_NOTIFY_MODEL,
 )
 from app.core.llm import complete
+from app.core.scheduler import send_useless_tip
 from app.core.weather import fetch_tomorrow_weather, judge_laundry
+from app.core.weather_cache import set_latest
 
 logger = logging.getLogger(__name__)
 
@@ -21,6 +23,7 @@ intents.message_content = True
 client = discord.Client(intents=intents)
 
 WEATHER_KEYWORDS = ("天気", "天候", "洗濯", "雨", "気温", "降水")
+USELESS_TALK_KEYWORDS = ("どうでもいい", "雑談", "暇", "つまんない", "退屈")
 
 
 async def _build_weather_context() -> str:
@@ -29,6 +32,7 @@ async def _build_weather_context() -> str:
         weather_data = await fetch_tomorrow_weather(WEATHER_AREA_CODE, WEATHER_AREA_KEYWORD)
         judgement, reason = judge_laundry(weather_data["weather"], weather_data["pop"])
         pop_text = f"{weather_data['pop']}%" if weather_data["pop"] is not None else "不明"
+        set_latest(weather_data["weather"], weather_data["pop"], judgement, reason)
         return (
             "【明日の天気予報データ（気象庁発表）】\n"
             f"天気: {weather_data['weather']}\n"
@@ -59,6 +63,12 @@ async def on_message(message: discord.Message):
 
     async with message.channel.typing():
         try:
+            if any(keyword in content for keyword in USELESS_TALK_KEYWORDS):
+                redirect = await _generate_useless_talk_redirect(content)
+                await message.reply(redirect)
+                await send_useless_tip()
+                return
+
             messages = [{"role": "system", "content": DISCORD_BOT_SYSTEM_PROMPT}]
 
             if any(keyword in content for keyword in WEATHER_KEYWORDS):
@@ -74,6 +84,27 @@ async def on_message(message: discord.Message):
             await message.reply("⚠️ 応答の生成に失敗しました")
 
 
+async def _generate_useless_talk_redirect(content: str) -> str:
+    """どうでもいい話を振られたとき、『どうでもいいTips』チャンネルへ誘導する一言を生成する。"""
+    fallback = "🤷 雑談なら『どうでもいいTips』チャンネルの出番です！今ちょうど一つ送りますね〜"
+
+    prompt = (
+        "あなたは「お天気アプリ」というDiscord Botです。"
+        "ユーザーがどうでもいい雑談を振ってきました。"
+        "あなたは天気専門なので、雑談は『どうでもいいTips』という別のBot/チャンネルにお任せしたいです。"
+        "そこへ話題を振るような、軽いノリの一言を1〜2文で返してください。"
+        "絵文字を1つ程度使い、出力は本文のみにしてください。\n\n"
+        f"ユーザーの発言: {content}"
+    )
+
+    try:
+        result = await complete([{"role": "user", "content": prompt}], model=WEATHER_NOTIFY_MODEL)
+        return result.strip() or fallback
+    except Exception:
+        logger.exception("Failed to generate useless talk redirect message")
+        return fallback
+
+
 async def start_discord_bot() -> None:
     if not DISCORD_BOT_TOKEN:
         logger.warning("DISCORD_BOT_TOKEN is not set; Discord bot will not start")