feat: add external API providers and central settings database

- Add central settings database client (system_settings on postgres-shared)
  - User-scoped settings with global fallback
  - API config storage with enabled/disabled toggle
  - Per-source category filtering for news

- Add modular external API providers in src/apis/:
  - OpenMeteoProvider: weather with geocoding (free, no key)
  - NOSProvider: Dutch news RSS feeds
  - BBCProvider: English news RSS feeds
  - AggregatedNewsProvider: merges sources with category filtering
  - AlphaVantageProvider: financial quotes (API key from settings DB)

- Add provider dependencies and lifecycle management
- Add requirements-dev.txt with pip-audit for security auditing
- Add MEMORY_REMEMBER_PLAN.md documenting volatile/document memory architecture

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/apis/__init__.py

@@ -0,0 +1,69 @@
+"""
+External API clients for Library Desk.
+
+This package contains clients for external web APIs, named by source.
+Each provider implements a common interface for interoperability.
+
+Weather providers (implement WeatherProvider):
+- openmeteo: Open-Meteo (free, no key)
+
+News providers (implement NewsProvider):
+- nos: NOS.nl Dutch RSS (free, no key)
+- bbc: BBC English RSS (free, no key)
+
+Financial providers (implement FinancialProvider):
+- alphavantage: Alpha Vantage (free tier with key)
+
+Users can swap providers by configuring which implementation to use.
+All providers return standardized response models from base.py.
+"""
+
+# Base classes and models
+from .base import (
+    # Enums
+    WeatherCondition,
+    # Weather models
+    CurrentWeather,
+    DayForecast,
+    WeatherForecast,
+    GeoLocation,
+    # News models
+    NewsItem,
+    NewsFeed,
+    # Financial models
+    StockQuote,
+    # Abstract providers
+    WeatherProvider,
+    NewsProvider,
+    FinancialProvider,
+)
+
+# Concrete implementations
+from .openmeteo import OpenMeteoProvider
+from .nos import NOSProvider
+from .bbc import BBCProvider
+from .news import AggregatedNewsProvider
+from .alphavantage import AlphaVantageProvider
+
+__all__ = [
+    # Enums
+    "WeatherCondition",
+    # Weather
+    "CurrentWeather",
+    "DayForecast",
+    "WeatherForecast",
+    "GeoLocation",
+    "WeatherProvider",
+    "OpenMeteoProvider",
+    # News
+    "NewsItem",
+    "NewsFeed",
+    "NewsProvider",
+    "NOSProvider",
+    "BBCProvider",
+    "AggregatedNewsProvider",
+    # Financial
+    "StockQuote",
+    "FinancialProvider",
+    "AlphaVantageProvider",
+]