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/injected_positions.json

@@ -0,0 +1,46 @@
+{
+  "_comment": "Injected positions file for GNSS Guard - Office Lab",
+  "_instructions": [
+    "1. Set position values for sources you want to inject (only those sources will use injected data)",
+    "2. Sources NOT in this file will be fetched from real sources normally",
+    "3. Set a source to 'null' to simulate its absence (skip fetching for that source)",
+    "4. Prefix a source key with '//' to comment it out (same as not including it)"
+  ],
+  "_fields": {
+    "latitude": "REQUIRED - Latitude in decimal degrees (used for distance validation)",
+    "longitude": "REQUIRED - Longitude in decimal degrees (used for distance validation)",
+    "timestamp_unix": "OPTIONAL - Unix timestamp in seconds (defaults to current time if absent)",
+    "altitude": "OPTIONAL - Altitude in meters (stored but NOT used for validation)",
+    "position_uncertainty_m": "OPTIONAL - Position uncertainty in meters (stored but NOT used for validation, Starlink only)"
+  },
+  "nmea_primary": {
+    "latitude": 36.11063,
+    "longitude": 22.972875,
+    "//timestamp_unix": 1768308542.0,
+    "altitude": 14.0
+  },
+  "nmea_secondary": {
+    "latitude": 36.11085833333333,
+    "longitude": 22.572023333333334,
+    "//timestamp_unix": 1732461600.0,
+    "altitude": 13.2
+  },
+  "tm_ais": {
+    "latitude": 36.110657,
+    "longitude": 22.572672,
+    "//timestamp_unix": 1732461600.0
+  },
+  "starlink_gps": {
+    "latitude": 36.11055287599966,
+    "longitude": 22.57289200819445,
+    "//timestamp_unix": 1732461600.0,
+    "altitude": 54.29000515150101
+  },
+  "starlink_location": {
+    "latitude": 36.11055187009735,
+    "longitude": 22.57289484169309,
+    "//timestamp_unix": 1732461600.0,
+    "altitude": 54.29000515150101,
+    "position_uncertainty_m": 2.5
+  }
+}