test(backend): add RPT log output to server stub

- Stub now parses -profiles= arg and writes RPT entries to
  profilesDir/arma3server_x64_<timestamp>.rpt
- RPT includes header (exe timestamp, computer name, OS) and periodic
  entries (MissionEditor, World, Server: Player) on each heartbeat cycle
- New test TestStart_StubWritesRPTLog verifies RPT file creation and
  content via the profiles directory

backend/internal/services/testdata/arma3server_x64

@@ -1,17 +1,39 @@
 #!/bin/sh
 # Stub arma3server binary for testing.
 # Logs binary path and all arguments, prints heartbeat every 5s.
+# Writes RPT log entries to the profiles directory (like the real server).
 # Use -t N to exit after N seconds (for auto-exit tests).
+
 echo "[STUB] binary=$0 args=$*"
 
 DURATION=0
+PROFILES_DIR=""
 while [ $# -gt 0 ]; do
   case "$1" in
     -t) DURATION="$2"; shift 2 ;;
+    -profiles=*) PROFILES_DIR="${1#-profiles=}"; shift ;;
     *)  shift ;;
   esac
 done
 
+# Create RPT file in profiles dir if provided
+RPT_FILE=""
+if [ -n "$PROFILES_DIR" ]; then
+  mkdir -p "$PROFILES_DIR"
+  RPT_FILE="$PROFILES_DIR/arma3server_x64_$(date +%Y%m%d_%H%M%S).rpt"
+  echo "--- RPT log started ---" > "$RPT_FILE"
+  echo "Exe timestamp: 2024/01/15 12:00:00" >> "$RPT_FILE"
+  echo "Computer name: STUB-TEST" >> "$RPT_FILE"
+  echo "Operating system: Linux" >> "$RPT_FILE"
+fi
+
+write_rpt() {
+  if [ -n "$RPT_FILE" ]; then
+    echo "$1" >> "$RPT_FILE"
+  fi
+}
+
+TICK=0
 if [ "$DURATION" -gt 0 ] 2>/dev/null; then
   ELAPSED=0
   while [ "$ELAPSED" -lt "$DURATION" ]; do
@@ -20,12 +42,21 @@ if [ "$DURATION" -gt 0 ] 2>/dev/null; then
     if [ "$REMAINING" -lt 5 ]; then WAIT=$REMAINING; fi
     sleep "$WAIT"
     ELAPSED=$((ELAPSED + WAIT))
+    TICK=$((TICK + 1))
     echo "[STUB] heartbeat elapsed=${ELAPSED}s remaining=$((REMAINING - WAIT))s"
+    write_rpt "$(date +%H:%M:%S) MissionEditor: Mission file selected: test_mission.Tanoa"
+    write_rpt "$(date +%H:%M:%S) World: Avoid neighbor island: 0.00 ms (1.00 ms)"
+    write_rpt "$(date +%H:%M:%S) Server: Player #1 connected (id=12345)"
   done
+  write_rpt "$(date +%H:%M:%S) Server: Shutdown completed"
   echo "[STUB] server exiting after ${DURATION}s"
 else
   while true; do
     sleep 5
+    TICK=$((TICK + 1))
     echo "[STUB] heartbeat running..."
+    write_rpt "$(date +%H:%M:%S) MissionEditor: Mission file selected: test_mission.Tanoa"
+    write_rpt "$(date +%H:%M:%S) World: Avoid neighbor island: 0.00 ms (1.00 ms)"
+    write_rpt "$(date +%H:%M:%S) Server: Player #1 connected (id=12345)"
   done
 fi