refactor(webchat): SwiftUI-only WebChat UI

# Conflicts:
#	apps/macos/Package.swift

test/format-error.test.ts

@@ -1,30 +0,0 @@
-import { describe, expect, it } from "vitest";
-import { formatError } from "../apps/macos/Sources/Clawdis/Resources/WebChat/format-error.js";
-
-describe("formatError", () => {
-  it("handles Error with stack", () => {
-    const err = new Error("boom");
-    err.stack = "stack trace";
-    expect(formatError(err)).toBe("stack trace");
-  });
-
-  it("handles CloseEvent-like object", () => {
-    const err = { code: 1006, reason: "socket closed", wasClean: false };
-    expect(formatError(err)).toBe("WebSocket closed (1006); reason: socket closed");
-  });
-
-  it("handles WebSocket error event with state", () => {
-    const err = { type: "error", target: { readyState: 2 } };
-    expect(formatError(err)).toBe("WebSocket error (state: closing)");
-  });
-
-  it("stringifies plain objects", () => {
-    expect(formatError({ a: 1 })).toBe("{\"a\":1}");
-  });
-
-  it("falls back to string", () => {
-    const circular = {} as any;
-    circular.self = circular;
-    expect(formatError(circular)).toBe("[object Object]");
-  });
-});