fix(delegate-task): resolve variant-bearing fallback models during immediate selection

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src/tools/delegate-task/model-string-parser.ts

@@ -9,7 +9,7 @@ const KNOWN_VARIANTS = new Set([
   "thinking",
 ])
 
-function parseVariantFromModelID(rawModelID: string): { modelID: string; variant?: string } {
+export function parseVariantFromModelID(rawModelID: string): { modelID: string; variant?: string } {
   const trimmedModelID = rawModelID.trim()
   if (!trimmedModelID) {
     return { modelID: "" }