fix(ui): show workspace launch errors in dialog

packages/ui/src/lib/launch-errors.ts

@@ -0,0 +1,29 @@
+export function formatLaunchErrorMessage(error: unknown, fallbackMessage: string): string {
+  if (!error) {
+    return fallbackMessage
+  }
+
+  const raw = typeof error === "string" ? error : error instanceof Error ? error.message : String(error)
+
+  try {
+    const parsed = JSON.parse(raw) as unknown
+    if (parsed && typeof parsed === "object" && "error" in parsed && typeof (parsed as any).error === "string") {
+      return (parsed as any).error
+    }
+  } catch {
+    // ignore JSON parse errors
+  }
+
+  return raw
+}
+
+export function isMissingBinaryMessage(message: string): boolean {
+  const normalized = message.toLowerCase()
+  return (
+    normalized.includes("opencode binary not found") ||
+    normalized.includes("binary not found") ||
+    normalized.includes("no such file or directory") ||
+    normalized.includes("binary is not executable") ||
+    normalized.includes("enoent")
+  )
+}