Reorganize core into subpackages, add local KB, ruff/pyright tooling

- Split backend/app/core into weather/, discord/, memory_kb/, search/
  subpackages by responsibility, keeping config.py and llm.py as the
  shared foundation; updated all import sites accordingly.
- Add local Markdown knowledge base support (local_knowledge.py,
  knowledge_base/fgo.md, LOCAL_KB_* settings) that embeds and injects
  relevant docs into the system prompt by topic similarity.
- Add ruff and pyright as backend dev dependencies with basic config
  in pyproject.toml for linting and type checking.
- Document local machine quirks in CLAUDE.md (Postgres on port 8080,
  SSLKEYLOGFILE breaking litellm/pyright via OPENSSL_Uplink crashes).
- Add backend/run_dev.ps1 dev launcher and docs/discord-bot.md.

backend/app/api/system.py

@@ -3,10 +3,10 @@ import psutil
 from pydantic import BaseModel
 from sqlalchemy.orm import Session as DBSession
 
-from app.core.scheduler import send_useless_tip, send_weather_laundry_notification
-from app.core.tagging import backfill_tags
-from app.core.weather_cache import get_latest as get_latest_weather
-from app.core.word_memory import get_word_pool_with_counts
+from app.core.discord.scheduler import send_useless_tip, send_weather_laundry_notification
+from app.core.memory_kb.tagging import backfill_tags
+from app.core.weather.weather_cache import get_latest as get_latest_weather
+from app.core.memory_kb.word_memory import get_word_pool_with_counts
 from app.db.database import get_db
 
 router = APIRouter(prefix="/api/system", tags=["system"])