Save workspace artifacts: character-controller, gdextension scaffold, network scripts, map-pipeline, server config

Includes code from task workspaces that was never pushed:
- client/characters/ — fps_character_controller.gd (400 lines), fps_camera.gd, input_handler.gd
- gdextension/simulation/ — C++ GDExtension scaffold: entity, movement, hit detection, simulation server, state serializer, bitstream (14 files)
- scripts/network/ — ENet-based network_manager.gd, server/client_main.gd, player.gd
- scripts/map_packaging/ — PCK pipeline: pack_map.gd, map_downloader.gd, map_registry_server.py, README
- scripts/config/ — server_config.gd (480 lines)
- scenes/ — client_main, server_main, player, test_range
- project.godot, export_presets.cfg

config-ext-map-registry.cfg

@@ -0,0 +1,21 @@
+; Tactical Shooter — Map Registry Configuration Extension
+; 
+; Add this section to your server_config.cfg to enable automatic
+; map downloading from the registry server.
+;
+; The MapDownloader Godot singleton reads these values at startup.
+; Environment override: MAP_REGISTRY_URL (takes precedence over cfg value)
+;
+; [map_registry]
+; enabled      — When true, the server fetches map list on start
+; url          — URL of the map registry server (HTTP/HTTPS)
+; auto_download_all  — Download ALL registry maps, not just rotation ones
+; max_cache_mb       — Soft limit on local cache size (0 = unlimited)
+; verify_checksums   — Verify SHA-256 on downloaded .pck files before loading
+
+[map_registry]
+enabled=false
+url="http://127.0.0.1:8090"
+auto_download_all=false
+max_cache_mb=500
+verify_checksums=true