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/guides/netfox-sharp.md

@@ -0,0 +1,98 @@
+# Netfox Sharp
+
+!!!warning
+    **[Netfox Sharp] is currently an experimental build and not ready for
+    production. During this time, breaking changes may be introduced at any
+    time.**
+
+The [Netfox Sharp] addon is designed to bridge the gap between GDScript and C#
+by allowing core netfox features to be accessed in C# without having to worry
+about [Cross-Language Scripting] with GDScript directly.
+
+### What Netfox Sharp Is
+
+- A wrapper for netfox that uses the existing netfox codebase for its logic.
+- A way to more conveniently call netfox logic in a C# environment.
+- Partially compatible with existing codebases that use GDScript.
+
+### What Netfox Sharp Isn't
+
+- A standalone addon written entirely in C#.
+- A perfect 1:1 translation. Due to quirks of netfox, some code will differ,
+  detailed below.
+- A wrapper for netfox.noray or netfox.extras. Support for either of those
+  currently isn't planned, but may be considered based on interest.
+
+## Getting Started
+
+- Download the [Netfox Sharp] repo, and move the `netfox_sharp` and
+  `netfox_sharp_internals` folders into the addons of a C#-enabled Godot
+  project using the .NET version of Godot 4.x.
+- Install the netfox addon. See the Netfox Sharp repo for details on which
+  version of netfox you need.
+- Build your project, then enable netfox and Netfox Sharp in your project
+  settings.
+- Restart Godot, and you've successfully set up Netfox Sharp!
+
+## Differences Between Netfox And Netfox Sharp
+
+Existing documentation for netfox should be easily translatable to Netfox Sharp
+by following the below differences.
+
+- Most changes follow Godot's rules for [Cross-Language Scripting], taking
+  netfox as the base. In netfox, consider the following:
+
+```gdscript
+# The following example is a snippet of netfox code
+func _ready():
+    NetworkTime.before_tick_loop.connect(_gather)
+
+func _gather():
+    # Input gathering here
+    pass
+
+func _rollback_tick(delta, tick, is_fresh):
+    # Rollback logic here
+    pass
+```
+
+Whereas in Netfox Sharp:
+
+```cs
+// This is functionally identical Netfox Sharp code
+public override void _Ready()
+{
+    // All netfox autoloads like NetworkTime are accessed through static members
+    // in NetfoxSharp, to save on GetNode() calls and reduce clutter in the
+    // project settings.
+
+    // All members like BeforeTickLoop are in PascalCase, similar to Godot's C#
+    NetfoxSharp.NetworkTime.BeforeTickLoop += Gather;
+}
+
+// As Gather is linked to a signal, it can be any naming convention.
+private void Gather()
+{
+    // Input gathering here
+}
+
+// Since _rollback_tick isn't connected to a signal and is instead handled by
+// netfox internally, netfox's naming convention must be followed.
+public void _rollback_tick(double delta, long tick, bool isFresh)
+{
+   // Rollback logic here
+}
+```
+
+- Nodes in the add mode menu have similar names to the GDScript version, but
+  with 'Sharp' affixed, IE `RollbackSynchronizerSharp`. The GDScript versions
+  of the nodes are also present in the add node menu. This is a limitation of
+  how netfox interacts with Godot and cannot be removed.
+
+# Other Notes
+- `RollbackSynchronizerSharp`, `StateSynchronizerSharp`, and
+  `TickInterpolatorSharp` create their own respective GDScript nodes, which are
+  instanced as internal children nodes and should not be accessed.
+
+[Cross-Language Scripting]: https://docs.godotengine.org/en/stable/tutorials/scripting/cross_language_scripting.html
+[Netfox Sharp]: https://github.com/CyFurStudios/NetfoxSharp/