Initial commit: Daily tech newsletter worker

A Node.js/TypeScript worker that sends daily AI-generated summaries
of tech news from X/Twitter via Nitter RSS feeds.

Features:
- Fetches tweets from 40+ curated tech accounts via Nitter RSS
- Filters and categorizes by topic (AI/ML, SWE, General Tech)
- Generates AI summaries using OpenRouter (Claude/GPT-4)
- Sends professional HTML email via Brevo SMTP
- Runs on cron schedule inside Docker container
- Instance rotation for Nitter reliability
- Graceful degradation if AI fails

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

.env.example

@@ -0,0 +1,52 @@
+# =============================================================================
+# APPLICATION
+# =============================================================================
+NODE_ENV=production
+LOG_LEVEL=info                          # debug, info, warn, error
+
+# =============================================================================
+# RSS CONFIGURATION
+# =============================================================================
+# Comma-separated list of Nitter instances (will rotate on failure)
+NITTER_INSTANCES=https://nitter.poast.org,https://xcancel.com,https://nitter.privacydev.net
+RSS_FETCH_TIMEOUT=30000                 # 30 seconds
+RSS_MAX_TWEETS_PER_ACCOUNT=50
+
+# =============================================================================
+# OPENROUTER AI
+# =============================================================================
+OPENROUTER_API_KEY=sk-or-v1-your-key-here
+OPENROUTER_MODEL=anthropic/claude-3-sonnet-20240229
+# Alternative models: openai/gpt-4-turbo, anthropic/claude-3-opus, google/gemini-pro
+OPENROUTER_MAX_TOKENS=2000
+OPENROUTER_SITE_URL=https://your-newsletter.com
+OPENROUTER_SITE_NAME=Tech Newsletter
+
+# =============================================================================
+# BREVO SMTP
+# =============================================================================
+BREVO_SMTP_HOST=smtp-relay.brevo.com
+BREVO_SMTP_PORT=587
+BREVO_SMTP_USER=your-brevo-login-email
+BREVO_SMTP_KEY=your-brevo-smtp-api-key
+EMAIL_FROM_ADDRESS=newsletter@yourdomain.com
+EMAIL_FROM_NAME=Daily Tech Digest
+# Comma-separated recipient list
+EMAIL_RECIPIENTS=you@example.com
+
+# =============================================================================
+# SCHEDULER
+# =============================================================================
+# Cron expression: minute hour day month weekday
+# Default: Every day at 7:00 AM
+CRON_SCHEDULE=0 7 * * *
+CRON_TIMEZONE=Europe/Warsaw
+
+# =============================================================================
+# FEATURE FLAGS
+# =============================================================================
+ENABLE_AI_SUMMARIES=true
+INCLUDE_RETWEETS=false
+INCLUDE_REPLIES=false
+# Set true to skip email sending (for testing)
+DRY_RUN=false