Phase 7: test server deployment + Windows export

- Fix: export_presets.cfg — platform='Windows Desktop' (correct name)
- Fix: server_main.gd — formatting bug on lag-comp string
- Fix: game_server.gd — auto-detect GDExtension, fall back to GDScript stub
- Add: server/scripts/simulation_server_stub.gd — lightweight SimulationServer in GDScript
- Add: docs/playtest-guide.md — connection instructions, control bindings, server commands
- Add: systemd user service — tactical-shooter-server (enabled, running)
- Add: server config at ~/tactical-shooter-server/server_config.cfg
- Build: Windows 109MB PE32+ client (build/tactical-shooter-windows-x86_64/)
- Build: Linux server binary (78MB) — running on oplabs:34197
- Temporarily disabled GDExtension (needs C++ build fix in entity.cpp enum casting)

client/scripts/convert_csg_to_mesh.gd.uid

@@ -0,0 +1 @@
+uid://c0b8h1hq57lsu

client/scripts/generate_occluders.gd.uid

@@ -0,0 +1 @@
+uid://pauclwpn265a

client/scripts/profiling/profile_scene.gd.uid

@@ -0,0 +1 @@
+uid://byjqslju7qnt6

client/scripts/profiling/profiler_node.gd.uid

@@ -0,0 +1 @@
+uid://jih7knhnl55a

client/scripts/profiling/test_process.gd.uid

@@ -0,0 +1 @@
+uid://dc8x14rs2jyu8

client/scripts/profiling/test_simple.gd.uid

@@ -0,0 +1 @@
+uid://b8jj7n3bi6ljh