Initial MVP: drivable RX-7 vertical slice + server-authoritative systems

- Rojo + Wally project; ProfileStore (loleris) for safe saves
- Shared: GameConfig, Cars (RX-7 free starter), ProfileTemplate, Remotes
- Server: DataManager, Economy, CarManager, RaceManager, MapBuilder, AntiCheat
- Client: neon HUD + Garage/Dealership UI (buy/equip/upgrade), race/daily
- Procedural Tokyo expressway (spawn pad, finish line, neon pylons, kill walls)
- CI workflow (Gitea/GitHub), Makefile, selene+stylua clean, rojo builds
- Docs: README, GDD, realistic solo ROADMAP

src/server/AntiCheat.luau

@@ -0,0 +1,81 @@
+--!strict
+--[[
+	AntiCheat.luau  (SERVER)
+	MVP-level movement sanity check. Not a fortress — a speed bump that catches
+	obvious speed/teleport hacks. Because money & car ownership are ALREADY
+	server-authoritative (Economy validates everything), the main client attack
+	surface left is movement, so we watch that.
+
+	Approach: sample each player's HRP position periodically; if they cover
+	ground implying a sustained speed above MaxPlausibleSpeed, snap them back
+	to their last valid position. Generous threshold to avoid false positives
+	from legit fast cars.
+]]
+
+local Players = game:GetService("Players")
+local RunService = game:GetService("RunService")
+local ReplicatedStorage = game:GetService("ReplicatedStorage")
+
+local GameConfig = require(ReplicatedStorage.Shared.GameConfig)
+
+local AntiCheat = {}
+
+type Track = { lastPos: Vector3, lastValid: CFrame }
+
+local tracked: { [Player]: Track } = {}
+local SAMPLE_INTERVAL = 0.5
+
+local function hrpOf(player: Player): BasePart?
+	local char = player.Character
+	return char and char:FindFirstChild("HumanoidRootPart") :: BasePart?
+end
+
+function AntiCheat.init()
+	local function watch(player: Player)
+		player.CharacterAdded:Connect(function(char)
+			local hrp = char:WaitForChild("HumanoidRootPart", 10) :: BasePart?
+			if hrp then
+				tracked[player] = { lastPos = hrp.Position, lastValid = hrp.CFrame }
+			end
+		end)
+	end
+	for _, p in ipairs(Players:GetPlayers()) do
+		watch(p)
+	end
+	Players.PlayerAdded:Connect(watch)
+	Players.PlayerRemoving:Connect(function(p)
+		tracked[p] = nil
+	end)
+
+	local accum = 0
+	RunService.Heartbeat:Connect(function(dt)
+		accum += dt
+		if accum < SAMPLE_INTERVAL then
+			return
+		end
+		local interval = accum
+		accum = 0
+
+		for player, track in pairs(tracked) do
+			local hrp = hrpOf(player)
+			if not hrp then
+				continue
+			end
+			local pos = hrp.Position
+			-- Falling doesn't count (avoid flagging big drops). Only guard XZ plane.
+			local horizontal = Vector3.new(pos.X - track.lastPos.X, 0, pos.Z - track.lastPos.Z).Magnitude
+			local hSpeed = horizontal / interval
+
+			if hSpeed > GameConfig.MaxPlausibleSpeed then
+				-- Snap back: likely a speed/teleport hack.
+				hrp.CFrame = track.lastValid
+				hrp.AssemblyLinearVelocity = Vector3.zero
+			else
+				track.lastValid = hrp.CFrame
+			end
+			track.lastPos = hrp.Position
+		end
+	end)
+end
+
+return AntiCheat