i18n: localize optimization source viewer and protect pending reads

AppImage/lib/optimization-source-errors.ts

@@ -0,0 +1,18 @@
+type Translate = (key: string, params?: Record<string, string | number>) => string
+
+export interface OptimizationSourceError {
+  kind: "unavailable" | "loadFailed"
+  detail?: string
+}
+
+// Keep the blueprint's English API contract intact; translate only its display.
+export function optimizationSourceError(error: OptimizationSourceError, t: Translate): string {
+  const detail = error.detail || ""
+  const key = "settings.optimizations."
+  if (detail === "Function not found in available scripts") return t(key + "sourceFunctionMissing")
+  if (detail.startsWith("Unknown tool: ")) return t(key + "sourceUnknownTool", { tool: detail.slice(14) })
+  if (detail.startsWith("No function mapping for ")) return t(key + "sourceNoMapping", { tool: detail.slice(24) })
+  if (detail === "Source code not available") return t(key + "sourceUnavailable")
+  const message = t(key + (error.kind === "unavailable" ? "sourceUnavailable" : "sourceLoadFailed"))
+  return detail ? `${message} ${detail}` : message
+}