feat(config): add JSON structured logging and syslog forwarding for application logs

- Add LOG_FORMAT setting (text/json) for structured JSON log output
- Add LOG_SYSLOG_* settings for direct syslog forwarding of app logs
- JSON format compatible with Grafana Loki, Splunk, ELK, Datadog
- Syslog forwarding uses Python's SysLogHandler (UDP/TCP)
- Update .env.demo and ConfigurationGuide.md with all new settings
- Add tests for JSON formatter and syslog config fields

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

.env.demo

@@ -14,6 +14,17 @@ COMPLIANCE_ENABLED=true  # Enable compliance templates dashboard (GDPR, HIPAA, S
 # LOG_LEVEL=INFO
 # DEBUG=false
 
+# Log output format: "text" (human-readable, default) or "json" (structured JSON lines).
+# Use "json" when shipping logs to Grafana Loki, Splunk, ELK, Datadog, or any SIEM.
+# LOG_FORMAT=text
+
+# Forward application logs to a syslog receiver (in addition to stdout).
+# Useful for traditional (non-container) deployments and centralised SIEM ingestion.
+# LOG_SYSLOG_ENABLED=false
+# LOG_SYSLOG_HOST=localhost
+# LOG_SYSLOG_PORT=514
+# LOG_SYSLOG_PROTOCOL=udp          # udp | tcp
+
 # **UI / Appearance**
 # Default colour scheme: system (follow OS), light, or dark
 # Individual users can always override with the navbar dark-mode toggle.