Fresh start: replace with naxIO/netfox-cs-sample foundation

Complete replacement of the tactical-shooter project with the
netfox-cs-sample (MIT) — a CS 1.6 inspired multiplayer FPS built
with Godot 4 and netfox.

## What's new
- Full CS-style gameplay: teams (T/CT), rounds, economy, buy menu
- 6 weapons: Knife, Glock, USP, AK-47, M4A1, AWP
- Bomb plant/defuse with 2 bombsites
- Flashbang & smoke grenades
- Proper netfox rollback netcode at 64 tick
- Network popup UI for host/join
- HUD, crosshair, round timer, scoreboard
- All netfox singletons registered as autoloads (works in exported builds)

## Architecture
- Listen-server (host from client, no dedicated server binary)
- Multiplayer-fps game lives at examples/multiplayer-fps/
- Netfox addons registered as autoloads for exported build compat
- Godot 4.7 with Forward+ renderer

## Removed
- Old headless-server architecture (client_main, server_main, player.gd, etc.)
- Custom netfox bootstrap with ENet fallback
- Old ChaffGames FPS template (2,420 lines, 844 KB)
- SimulationServer GDExtension stub
- Godot-jolt physics (netfox sample uses default Godot physics)
- Duplicate weapon_data.gd, anti_cheat.gd, round_manager.gd, etc.
- Server browser API Python venv (87 MB)
- test_range map and modular assets

## Preserved
- Git history
- Server config at config/default_server_config.cfg
- Windows export preset
- Build directory (gitignored)

Co-authored-by: naxIO <naxIO@users.noreply.github.com>

docs/netfox/tutorials/using-rollbacksynchronizer-without-inputs.md

@@ -0,0 +1,26 @@
+# Using RollbackSynchronizer without inputs
+
+In certain cases, a component needs to participate in rollback, but is not
+driven by any input. One example could be more complex NPCs. These need to be
+part of the rollback tick loop, but they are not controlled by any player.
+
+In these cases, you can use RollbackSynchronizer as described earlier in
+[Responsive player movement], but without the input. This means not needing an
+input node, and not configuring any input properties. State properties still
+need to be configured, and the gameplay logic must be implemented in
+`_rollback_tick()`.
+
+!!!tip
+    An example project featuring a simple NPC using an inputless
+    RollbackSynchronizer can be found at [examples/rollback-npc].
+
+Under the hood, *netfox* will simulate these inputless nodes whenever it
+encounters a tick that has no state for the inputless node. On the server, this
+means inputless nodes will be simulated only for new ticks. On clients, this
+means never being simulated, since all state is received from the server. If
+prediction is enabled, clients will simulate inputless nodes for ticks they
+don't have data from the server.
+
+
+[Responsive player movement]: ./responsive-player-movement.md
+[examples/rollback-npc]: https://github.com/foxssake/netfox/tree/main/examples/rollback-npc