fix(runtime-fallback): consume delegated bootstrap retry payload

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/hooks/runtime-fallback/index.test.ts

@@ -551,6 +551,7 @@ describe("runtime-fallback", () => {
       expect(promptBody?.tools?.question).toBe(false)
       expect(promptBody?.tools?.call_omo_agent).toBe(true)
       expect(promptBody?.parts?.[0]?.text).toContain("inspect src/tools/delegate-task")
+      expect(getDelegatedChildSessionBootstrap(sessionID)).toBeUndefined()
     })
 
     test("should use persisted user prompt while preserving delegated bootstrap launch context", async () => {

src/hooks/runtime-fallback/last-user-retry-parts.ts

@@ -54,8 +54,13 @@ export function getLastUserRetryPayload(
     return { retryParts }
   }
 
+  const bootstrapRetryParts = bootstrap?.retryParts ?? []
+  if (bootstrapRetryParts.length > 0) {
+    clearDelegatedChildSessionBootstrap(sessionID)
+  }
+
   return {
-    retryParts: bootstrap?.retryParts ?? [],
+    retryParts: bootstrapRetryParts,
     ...(bootstrap?.system ? { system: bootstrap.system } : {}),
     ...(bootstrap?.tools ? { tools: bootstrap.tools } : {}),
   }