feat: productionize local service — fix signal pipeline, lower thresholds, add company-name ticker extraction

- Point Ollama to local instance via host.docker.internal, use gemma3 model
- Remove Docker Ollama service (using host's Ollama instead)
- Add company-name-to-ticker mapping (Apple→AAPL, Tesla→TSLA, etc.) for RSS articles
- Lower signal thresholds for faster feedback with paper trading:
  - FinBERT confidence: 0.6→0.4, signal strength: 0.3→0.15
  - News strategy: article_count 2→1, confidence 0.5→0.3, score ±0.3→±0.15
- Fix market data BarSet access bug (BarSet.__contains__ returns False incorrectly)
- Fix market data SIP feed error by switching to IEX feed for free Alpaca accounts
- Fix nginx proxy routing for /api/auth/* to api-gateway /auth/*
- Add seed_sample_data script
- Update tests for new thresholds and alpaca mock modules

.env.example

@@ -29,8 +29,9 @@ TRADING_REDDIT_CLIENT_ID=your_client_id
 TRADING_REDDIT_CLIENT_SECRET=your_client_secret
 TRADING_REDDIT_USER_AGENT=trading-bot/0.1
 
-# Ollama — use Docker service name inside compose
-TRADING_OLLAMA_HOST=http://ollama:11434
+# Ollama — use host.docker.internal if running Ollama on the host machine
+TRADING_OLLAMA_HOST=http://host.docker.internal:11434
+TRADING_OLLAMA_MODEL=gemma3
 
 # WebAuthn — update for production domain
 TRADING_RP_ID=localhost