feat(chat): group batched tool calls into one DaisyUI list

Consume the backend's new stepId grouping key (wire/transport-contract
0.1.0 -> 0.2.0). foldEvent copies event.stepId onto live tool chunks so
live and replay group identically. New pure selector groupRenderedChunks
(core/chunks) folds a step's 2+ tool calls into one tool-batch group,
pairing each call with its result by toolCallId; single/no-stepId calls
stay as cards. ChatView renders a batch as a DaisyUI list (list-row per
pair). Fixtures updated for the now-required event stepId.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/features/chat/store.test.ts b/src/features/chat/store.test.ts
index de60b14..71781ac 100644
--- a/src/features/chat/store.test.ts
+++ b/src/features/chat/store.test.ts
@@ -1,4 +1,4 @@
-import type { AgentEvent, StoredChunk } from "@dispatch/wire";
+import type { AgentEvent, StepId, StoredChunk } from "@dispatch/wire";
 import { describe, expect, it, vi } from "vitest";
 import { createChatStore } from "./store.svelte";
 import { createFakeCache, createFakeHistorySync, createFakeTransport } from "./test-helpers";
@@ -327,6 +327,7 @@ describe("createChatStore", () => {
 				toolCallId: "tc1",
 				toolName: "read_file",
 				input: { path: "/tmp/test.txt" },
+				stepId: "t1#0" as StepId,
 			}),
 		);
 		store.handleDelta(
@@ -338,6 +339,7 @@ describe("createChatStore", () => {
 				toolName: "read_file",
 				content: "file contents",
 				isError: false,
+				stepId: "t1#0" as StepId,
 			}),
 		);