test(ralph-loop): remove unsafe fixture assertions

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

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

src/hooks/ralph-loop/completion-promise-detector.test.ts

@@ -1,7 +1,7 @@
 /// <reference types="bun-types" />
 import { describe, expect, test } from "bun:test"
 import { detectCompletionInSessionMessages } from "./completion-promise-detector"
-import { createPluginInput } from "./completion-promise-detector-test-input"
+import { createPluginInput } from "./completion-promise-detector-test-input.test"
 
 describe("detectCompletionInSessionMessages", () => {
   describe("#given session with prior DONE and new messages", () => {