Scope cut: drive-only MVP (remove racing + economy)

Per user direction, the MVP is now simply driving cars on the expressway.
- Removed RaceManager and Economy modules entirely
- Slimmed Remotes to DataUpdated / SpawnCar / EquipCar
- ProfileTemplate now just remembers the last driven car (v2)
- Cars: dropped price/rep/upgrade fields; kept identity + driving stats
- CarManager: stat-based tuning only; RX-7 allowlist via GameConfig.canDrive
- DataManager: assign default car on join; downgrade RX-7 if de-allowlisted
- Client: replaced garage/economy UI with a simple car picker + respawn
- Docs: GDD/ROADMAP/README rewritten for drive-only; added docs/MESH_SWAP.md
- Gates: stylua clean, selene 0/0, rojo builds

src/server/DataManager.luau

@@ -71,20 +71,14 @@ local function onPlayerAdded(player: Player)
 	profile:AddUserId(player.UserId) -- GDPR-friendly association
 	profile:Reconcile() -- fill missing template keys
 
-	-- Grant the correct starter car for THIS player (RX-7 only for allowlisted
-	-- UserIds; everyone else gets the public starter). Idempotent: only grants
-	-- if the player has no cars yet (i.e. genuinely first join).
+	-- Assign the player's default car if they don't have one yet, and validate:
+	-- if their saved car is the restricted RX-7 but they're no longer allowlisted,
+	-- fall back to the public default so they can still drive.
 	local data = profile.Data
-	if #data.OwnedCars == 0 then
-		local starterId = GameConfig.starterCarFor(player.UserId)
-		table.insert(data.OwnedCars, {
-			Id = starterId,
-			Upgrades = { Engine = 0, Tires = 0, Nitro = 0 },
-		})
-		data.EquippedCarId = starterId
-	elseif data.EquippedCarId == "" then
-		-- Safety: if somehow they own cars but have nothing equipped, equip the first.
-		data.EquippedCarId = data.OwnedCars[1].Id
+	if data.EquippedCarId == "" then
+		data.EquippedCarId = GameConfig.defaultCarFor(player.UserId)
+	elseif data.EquippedCarId == GameConfig.RestrictedCarId and not GameConfig.isRX7Allowed(player.UserId) then
+		data.EquippedCarId = GameConfig.PublicDefaultCarId
 	end
 
 	profile.OnSessionEnd:Connect(function()