feat: 記事ごとのポッドキャスト生成と新規記事検出システム、モダンUIの実装

- 新規記事検出システム: 記事の重複チェックと新規記事のみ処理
- 記事単位ポッドキャスト: フィード統合から記事個別エピソードに変更
- 6時間間隔バッチ処理: 自動定期実行スケジュールの改善
- 完全UIリニューアル: ダッシュボード・フィード管理・エピソード管理の3画面構成
- アクセシビリティ強化: ARIA属性、キーボードナビ、高コントラスト対応
- データベース刷新: feeds/articles/episodes階層構造への移行
- 中央集権設定管理: services/config.ts による設定統一
- エラーハンドリング改善: 全モジュールでの堅牢なエラー処理
- TypeScript型安全性向上: null安全性とインターフェース改善

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

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

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Common Development Commands
+
+- **Install dependencies**: `bun install`
+- **Build frontend**: `bun run build:frontend`
+- **Start server**: `bun run start` or `bun run server.ts`
+- **Frontend development**: `bun run dev:frontend`
+- **Manual batch process**: `bun run scripts/fetch_and_generate.ts`
+- **Type checking**: `bunx tsc --noEmit`
+
+## Architecture Overview
+
+This is a RSS-to-podcast automation system built with Bun runtime, Hono web framework, React frontend, and SQLite database.
+
+### Core Components
+
+- **server.ts**: Main Hono web server serving both API endpoints and static frontend files
+- **scripts/fetch_and_generate.ts**: Batch processing script that fetches RSS feeds, generates summaries, and creates audio files
+- **services/**: Core business logic modules:
+  - `config.ts`: Centralized configuration management with validation
+  - `database.ts`: SQLite operations for episodes and feed tracking
+  - `llm.ts`: OpenAI integration for content generation and feed classification
+  - `tts.ts`: Text-to-speech via VOICEVOX API
+  - `podcast.ts`: RSS feed generation
+- **frontend/**: Vite React SPA for browsing feeds and episodes
+
+### Data Flow
+
+1. RSS feeds listed in `feed_urls.txt` are processed daily
+2. Latest articles are classified by category and summarized via OpenAI
+3. Summaries are converted to audio using VOICEVOX
+4. Episodes are stored in SQLite (`data/podcast.db`) with audio files in `public/podcast_audio/`
+5. RSS feed is generated at `/podcast.xml` for podcast clients
+6. Web UI serves the React frontend for browsing content
+
+### Key Directories
+
+- `data/`: SQLite database storage
+- `public/podcast_audio/`: Generated MP3 files
+- `frontend/dist/`: Built React application (served statically)
+
+### Environment Configuration
+
+The application uses `services/config.ts` for centralized configuration management. Required `.env` variables include:
+- `OPENAI_API_KEY`: OpenAI API key (required)
+- `VOICEVOX_HOST`: VOICEVOX server URL (default: http://localhost:50021)
+- `VOICEVOX_STYLE_ID`: Voice style ID (default: 0)
+- Podcast metadata and other optional settings
+
+Configuration is validated on startup. See README.md for complete list.
+
+### Deployment
+
+The application runs as a single server process on port 3000, automatically executing batch processing on startup and daily at midnight.
+
+### Recent Improvements
+
+- **ES Module Compatibility**: Fixed all ES module issues and removed deprecated `__dirname` usage
+- **Centralized Configuration**: Added `services/config.ts` for type-safe configuration management
+- **Enhanced Error Handling**: Improved error handling and validation throughout the codebase
+- **Type Safety**: Fixed TypeScript errors and added proper null checks
+- **Code Structure**: Simplified RSS generation logic and removed code duplication
+- **Path Resolution**: Standardized path handling using the config module