Phase 8: Headless dedicated server + RCON admin + netfox bootstrap

## Headless Server
- New entry point: scenes/headless_server.tscn + scripts/headless_server.gd
- Loads multiplayer-fps game, strips UI/rendering, auto-hosts ENet server
- Port config via --port arg, SERVER_PORT env, or default 34197
- RCON admin console on port 28960 (configurable via --rcon-port)

## Netfox Headless Bootstrap
- scripts/netfox_headless_bootstrap.gd — preloads all netfox dependency
  scripts in headless mode so class_names register before autoloads parse
- Registered as first autoload in project.godot
- Fixes 'Could not find type' errors for NetfoxLogger, NorayProtocolHandler,
  NetworkClocks, etc.

## RCON Admin
- Ported from old project: scripts/rcon/rcon_server.gd (TCP auth layer)
- scripts/rcon/rcon_command_handler.gd (command dispatch)
- Password via config/rcon_password.cfg, --rcon-password, or RCON_PASSWORD env

## Other Changes
- Added GameEvents stub (lan-bootstrapper dependency)
- Updated project.godot features to 4.7
- Added config/server_config.cfg for operator editing
- Updated RCON paths to new project structure

scenes/headless_server.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://headless_server"]
+
+[ext_resource type="Script" path="res://scripts/headless_server.gd" id="1"]
+
+[node name="HeadlessServer" type="Node"]
+script = ExtResource("1")