Fix Bun mock.module() leak between test files preventing ralph-loop tests from passing

Replace mock.module() with spyOn() in auto-slash-command test to prevent shared module mocking from leaking to other test files. Remove unused mock.module() from think-mode test. This ensures test isolation so ralph-loop tests pass in both isolation and full suite runs.

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src/hooks/think-mode/index.test.ts

@@ -1,12 +1,6 @@
-import { describe, expect, it, beforeEach, mock } from "bun:test"
+import { describe, expect, it, beforeEach } from "bun:test"
 import type { ThinkModeInput } from "./types"
 
-const logMock = mock(() => {})
-
-mock.module("../../shared", () => ({
-  log: logMock,
-}))
-
 const { createThinkModeHook, clearThinkModeState } = await import("./index")
 
 /**