Default to localhost for workstation install

- ConnectionPanel defaults host to localhost, blank username
- Backend OLLAMA_URL defaults to localhost:11434
- Systemd service reads /etc/llm-trainer/env for overrides

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packaging/build-deb.sh

@@ -88,6 +88,7 @@ Restart=always
 RestartSec=5
 StandardOutput=append:/var/log/llm-trainer/backend.log
 StandardError=append:/var/log/llm-trainer/backend.log
+EnvironmentFile=-/etc/llm-trainer/env
 Environment=PYTHONUNBUFFERED=1
 
 [Install]
@@ -137,6 +138,15 @@ fi
 chown -R llm-trainer:llm-trainer /opt/llm-trainer
 chown -R llm-trainer:llm-trainer /var/log/llm-trainer
 
+# Write default env config (only on first install)
+if [ ! -f /etc/llm-trainer/env ]; then
+  cat > /etc/llm-trainer/env <<'ENV'
+# LLM Trainer configuration
+# Override Ollama URL if it runs on a different host
+OLLAMA_URL=http://localhost:11434
+ENV
+fi
+
 # Build Python venv and install deps
 echo "Installing Python dependencies..."
 python3 -m venv /opt/llm-trainer/venv