Update syncback feature to handle instance pulling from Studio

- Updated the `ServeSession` to implement logic for pulling instances that exist in Studio but not in Rojo's filesystem, creating appropriate files during sync confirmation.
- Introduced a new `encodeInstance` function to serialize Studio instances for transmission, supporting all instance types.
- Modified the `PatchTree` to allow explicit user selection for push/pull/skip actions, enhancing user control during sync operations.
- Added tests for the new encoding functionality and updated existing tests to ensure proper behavior with the new syncback logic.

plugin/src/ChangeBatcher/encodeInstance.spec.lua

@@ -0,0 +1,160 @@
+return function()
+	local encodeInstance = require(script.Parent.encodeInstance)
+
+	describe("encodeInstance", function()
+		describe("script encoding", function()
+			it("should encode ModuleScript correctly", function()
+				local moduleScript = Instance.new("ModuleScript")
+				moduleScript.Name = "TestModule"
+				moduleScript.Source = "return {}"
+
+				local encoded = encodeInstance(moduleScript, "PARENT_ID")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.parent).to.equal("PARENT_ID")
+				expect(encoded.name).to.equal("TestModule")
+				expect(encoded.className).to.equal("ModuleScript")
+				expect(encoded.properties).to.be.ok()
+				expect(encoded.properties.Source).to.be.ok()
+
+				moduleScript:Destroy()
+			end)
+
+			it("should encode Script correctly", function()
+				local script = Instance.new("Script")
+				script.Name = "TestScript"
+				script.Source = "print('hello')"
+
+				local encoded = encodeInstance(script, "PARENT_ID")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.name).to.equal("TestScript")
+				expect(encoded.className).to.equal("Script")
+				expect(encoded.properties.Source).to.be.ok()
+
+				script:Destroy()
+			end)
+
+			it("should encode LocalScript correctly", function()
+				local localScript = Instance.new("LocalScript")
+				localScript.Name = "TestClient"
+				localScript.Source = "print('client')"
+
+				local encoded = encodeInstance(localScript, "PARENT_ID")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.name).to.equal("TestClient")
+				expect(encoded.className).to.equal("LocalScript")
+				expect(encoded.properties.Source).to.be.ok()
+
+				localScript:Destroy()
+			end)
+		end)
+
+		describe("folder encoding", function()
+			it("should encode Folder correctly", function()
+				local folder = Instance.new("Folder")
+				folder.Name = "TestFolder"
+
+				local encoded = encodeInstance(folder, "PARENT_ID")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.parent).to.equal("PARENT_ID")
+				expect(encoded.name).to.equal("TestFolder")
+				expect(encoded.className).to.equal("Folder")
+				-- Folders have no special properties
+				expect(encoded.properties).to.be.ok()
+
+				folder:Destroy()
+			end)
+		end)
+
+		describe("other instance encoding", function()
+			it("should encode Part with properties", function()
+				local part = Instance.new("Part")
+				part.Name = "TestPart"
+				part.Anchored = true
+
+				local encoded = encodeInstance(part, "PARENT_ID")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.name).to.equal("TestPart")
+				expect(encoded.className).to.equal("Part")
+				expect(encoded.properties).to.be.ok()
+				-- Properties should be captured
+				-- Note: Exact properties depend on RbxDom descriptors
+
+				part:Destroy()
+			end)
+
+			it("should encode StringValue", function()
+				local stringValue = Instance.new("StringValue")
+				stringValue.Name = "TestValue"
+				stringValue.Value = "Hello World"
+
+				local encoded = encodeInstance(stringValue, "PARENT_ID")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.name).to.equal("TestValue")
+				expect(encoded.className).to.equal("StringValue")
+
+				stringValue:Destroy()
+			end)
+
+			it("should encode Configuration", function()
+				local config = Instance.new("Configuration")
+				config.Name = "TestConfig"
+
+				local encoded = encodeInstance(config, "PARENT_ID")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.className).to.equal("Configuration")
+
+				config:Destroy()
+			end)
+		end)
+
+		describe("parent ID handling", function()
+			it("should include parent ID in all encodings", function()
+				local instances = {
+					Instance.new("ModuleScript"),
+					Instance.new("Folder"),
+					Instance.new("Part"),
+				}
+
+				for _, instance in instances do
+					local encoded = encodeInstance(instance, "UNIQUE_PARENT_ID")
+					expect(encoded).to.be.ok()
+					expect(encoded.parent).to.equal("UNIQUE_PARENT_ID")
+					instance:Destroy()
+				end
+			end)
+		end)
+
+		describe("edge cases", function()
+			it("should handle instances with special characters in name", function()
+				local folder = Instance.new("Folder")
+				folder.Name = "Test Folder (1)"
+
+				local encoded = encodeInstance(folder, "PARENT")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.name).to.equal("Test Folder (1)")
+
+				folder:Destroy()
+			end)
+
+			it("should handle instances with empty name", function()
+				local folder = Instance.new("Folder")
+				folder.Name = ""
+
+				local encoded = encodeInstance(folder, "PARENT")
+
+				expect(encoded).to.be.ok()
+				expect(encoded.name).to.equal("")
+
+				folder:Destroy()
+			end)
+		end)
+	end)
+end