Refactor golden image handling in backup upload process</message>

<message>Update the _set_golden_from_path function to improve the handling of existing golden image files. Replace the existing unlink logic with a more robust method that safely removes files or broken symlinks using the missing_ok parameter. This change enhances the reliability of the backup upload process by ensuring that stale references are properly cleared before setting a new golden image path.

backup-from-device/gnss-guard/tm-gnss-guard/server/.env.prod

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+# =============================================================================
+# GNSS Guard Server Configuration
+# =============================================================================
+
+# =============================================================================
+# SERVER SETTINGS
+# =============================================================================
+
+# Host to bind to (127.0.0.1 when behind Nginx proxy)
+GNSS_SERVER_HOST=127.0.0.1
+
+# Port to bind to
+GNSS_SERVER_PORT=8000
+
+# Enable debug mode (set to false in production)
+GNSS_SERVER_DEBUG=false
+
+# =============================================================================
+# DATABASE (PostgreSQL RDS)
+# =============================================================================
+
+# Full database connection URL
+# Format: postgresql://USER:PASSWORD@HOST:PORT/DATABASE
+GNSS_SERVER_DATABASE_URL=postgresql://postgres:!ks-hUe8@gnss-guard.cn06uuuk8ttq.eu-west-1.rds.amazonaws.com:5432/gnss_guard
+
+# =============================================================================
+# SECURITY
+# =============================================================================
+
+# Secret key for session encryption (generate with: python -c "import secrets; print(secrets.token_urlsafe(32))")
+GNSS_SERVER_SECRET_KEY=e0QnYxAvisgbOqzTIl-rlLyczsNOpP7hEc26ea22ikI
+
+# Session expiration in minutes (default: 24 hours)
+GNSS_SERVER_SESSION_EXPIRE_MINUTES=1440
+
+# =============================================================================
+# WEB UI AUTHENTICATION
+# =============================================================================
+
+# Username for web dashboard login
+GNSS_SERVER_WEB_USERNAME=test
+
+# Password for web dashboard login
+GNSS_SERVER_WEB_PASSWORD=Tototheo.25!
+
+# =============================================================================
+# DOMAIN (for SSL/HTTPS)
+# =============================================================================
+
+# Server domain name (for Let's Encrypt SSL)
+GNSS_SERVER_DOMAIN=gnss.tototheo.com
+
+# =============================================================================
+# =============================================================================
+# VALIDATION
+# =============================================================================
+
+# Staleness threshold in seconds (data older than this is considered stale)
+GNSS_SERVER_STALE_THRESHOLD_SECONDS=60
+
+# DATA RETENTION
+# =============================================================================
+
+# Days to keep validation history (default: 90)
+GNSS_SERVER_VALIDATION_HISTORY_DAYS=90
+
+# Email for Let's Encrypt certificate notifications
+LETSENCRYPT_EMAIL=alexander.s@tototheo.com
+
+# ============================================================================
+# Telegram Bot Configuration (Optional)
+# ============================================================================
+# 1. Create bot: Open Telegram → Search @BotFather → /newbot
+# 2. Get chat ID:
+#    - Start chat with your bot, send any message
+#    - Visit: https://api.telegram.org/bot<YOUR_TOKEN>/getUpdates
+#    - Find "chat":{"id":123456789} (positive for DM, negative for groups)
+# 3. Fill in values below
+# 
+# Each asset can override the chat_id to send to a different chat/group.
+# ============================================================================
+
+GNSS_SERVER_TELEGRAM_BOT_TOKEN=8319259186:AAGfg2tHPlnHduAPvsnODLPA1kaRDIsbx0A
+GNSS_SERVER_TELEGRAM_CHAT_ID=-4863784324
+
+# =============================================================================
+# ASSET OFFLINE DETECTION
+# =============================================================================
+
+# Seconds without updates before an asset is considered offline (default: 120)
+# Triggers Telegram notification when asset goes offline/online
+GNSS_SERVER_ASSET_OFFLINE_SECONDS=120
+