fix(migrations): merge main and rechain compliance migration as 031 after 030_add_mobile_devices

Merge main branch into compliance templates feature branch.

Main had advanced with migrations 027-030 (ensure_shared_links,
audit_logs, user_language_preference, mobile_devices) since this
branch forked. Our compliance migration was 027 with down_revision
026, which conflicted with main's 027_ensure_shared_links_table.

Changes:
- Merge main (including i18n, audit logs, mobile, GraphQL features)
- Resolve conflicts in app/api/__init__.py, app/models.py, tests/conftest.py
- Rename 027_add_compliance_templates → 031_add_compliance_templates
- Rechain: down_revision 026_add_scheduled_jobs → 030_add_mobile_devices
- Add ComplianceTemplate to migrations/env.py imports
- Alembic now has single head: 031_add_compliance_templates

.env.demo

@@ -97,6 +97,22 @@ MAX_UPLOAD_SIZE=1073741824
 # Allowed request headers (use * to allow all)
 # CORS_ALLOWED_HEADERS=*
 
+# **Audit Logging & SIEM Integration** (see docs/ConfigurationGuide.md#audit-logging)
+# Enable HTTP request audit logging middleware
+AUDIT_LOGGING_ENABLED=true
+# Include client IP in audit log entries (disable for GDPR-sensitive deployments)
+AUDIT_LOG_INCLUDE_CLIENT_IP=true
+
+# Forward audit events to an external SIEM system (Syslog, Splunk, Logstash, Grafana, etc.)
+# AUDIT_SIEM_ENABLED=false
+# AUDIT_SIEM_TRANSPORT=syslog          # syslog | http
+# AUDIT_SIEM_SYSLOG_HOST=localhost
+# AUDIT_SIEM_SYSLOG_PORT=514
+# AUDIT_SIEM_SYSLOG_PROTOCOL=udp       # udp | tcp
+# AUDIT_SIEM_HTTP_URL=                  # e.g. https://splunk:8088/services/collector/event
+# AUDIT_SIEM_HTTP_TOKEN=                # Bearer / HEC token
+# AUDIT_SIEM_HTTP_CUSTOM_HEADERS=       # Comma-separated Key:Value pairs
+
 # **Rate Limiting** (see SECURITY_AUDIT.md and docs/API.md)
 # Protects against DoS attacks and API abuse by limiting request rates per IP/user
 # Enabled by default - highly recommended for production
@@ -511,3 +527,12 @@ EMBEDDING_MAX_TOKENS=8000
 # Attach PII (IP addresses, user agents) to Sentry events.
 # Disable (default) to stay GDPR/CCPA compliant.
 # SENTRY_SEND_DEFAULT_PII=false
+
+# **Mobile App – Push Notifications**
+# Push notifications are delivered via Expo's push notification service
+# (https://expo.dev/notifications) which routes to APNs (iOS) and FCM (Android).
+# No additional credentials are required on the server side.
+# The mobile app registers its Expo push token via POST /api/mobile/register-device.
+#
+# To use native FCM/APNs directly (without Expo relay), replace the
+# send_expo_push_notification function in app/utils/push_notification.py.