Nitro V3 update: CLI-only (Linux), settings via .env

- Moved Nitro V3 update from web UI (Commandocentrum) to CLI-only
- Removed configure paths form and runUpdateNitrov3() from admin panel
- update-Nitrov3.sh now loads .env automatically from its directory
- Added all NITRO_* env vars to .env.example.linux and .env
- Removed configurable paths from database (replaced by .env)
- Updated README and CHANGELOG

update-Nitrov3.sh

@@ -3,8 +3,15 @@
 # Strict mode: exit on any error, undefined var, or pipe failure
 set -euo pipefail
 
+# Laad .env bestand uit dezelfde directory als dit script
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+if [ -f "$SCRIPT_DIR/.env" ]; then
+    set -a
+    . "$SCRIPT_DIR/.env"
+    set +a
+fi
+
 # Real-time output via pseudo-terminal (unbuffer from expect)
-# Dit forceert line-buffered output voor ALLE commands, ook in web interfaces
 if [ -z "${_UNBUFFERED:-}" ] && command -v unbuffer &> /dev/null; then
     export _UNBUFFERED=1
     exec unbuffer bash "$0" "$@"
@@ -14,7 +21,7 @@ exec 2>&1
 # Trap for clean error messages
 trap 'echo "=== ❌ FOUT: Update mislukt op regel $LINENO (commando: $BASH_COMMAND) ===" >&2; exit 1' ERR
 
-# --- CONFIGURATION (overridable via environment variables) ---
+# --- CONFIGURATION (uit env vars, met defaults) ---
 DB_NAME="${NITRO_DB_NAME:-habbo}"
 DB_HOST="${NITRO_DB_HOST:-127.0.0.1}"
 DB_PORT="${NITRO_DB_PORT:-3306}"