Add syncback command handling to MCP stream and API

- Introduced a new `onSyncbackCommand` option in `McpStream` to handle syncback requests.
- Implemented the `handle_mcp_syncback` function in the API to process syncback requests, including validation and logging.
- Updated the `run_live_syncback` function to return statistics on added and removed files during the syncback process.
- Enhanced the MCP tools list to include the new syncback tool, with corresponding documentation added.

These changes aim to facilitate a complete syncback of the Roblox Studio state to the filesystem, improving project management capabilities.

plugin/src/McpStream.lua

@@ -28,6 +28,7 @@ function McpStream.new(options)
 
 	self._onSyncCommand = options.onSyncCommand
 	self._onGetScriptCommand = options.onGetScriptCommand
+	self._onSyncbackCommand = options.onSyncbackCommand
 	self._onToolCommand = options.onToolCommand
 	self._getPluginConfig = options.getPluginConfig
 	self._wsClient = nil
@@ -178,6 +179,33 @@ function McpStream:_tryConnect()
 						end)
 					end
 				end)
+		elseif data.type == "syncback" and data.requestId then
+			Log.info("MCP stream: received syncback command (requestId={})", data.requestId)
+
+			local resultPromise = self._onSyncbackCommand(data.requestId)
+
+			resultPromise
+				:andThen(function(result)
+					if self._wsClient then
+						local json = HttpService:JSONEncode(result)
+						pcall(function()
+							self._wsClient:Send(json)
+						end)
+					end
+				end)
+				:catch(function(err)
+					Log.warn("MCP stream: syncback command failed: {}", tostring(err))
+					if self._wsClient then
+						local errorResult = HttpService:JSONEncode({
+							requestId = data.requestId,
+							status = "error",
+							response = tostring(err),
+						})
+						pcall(function()
+							self._wsClient:Send(errorResult)
+						end)
+					end
+				end)
 		elseif data.type and data.requestId and PASSTHROUGH_TOOLS[data.type] then
 			Log.info("MCP stream: received {} command (requestId={})", data.type, data.requestId)