test: make unsafe test coercion explicit

Move test coercion out of a hidden global and require each test to import the helper so review tools and runtime scripts can see the unsafe boundary.

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

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

src/hooks/no-sisyphus-gpt/index.test.ts

@@ -5,6 +5,7 @@ import type { PluginInput } from "@opencode-ai/plugin"
 import { _resetForTesting, updateSessionAgent } from "../../features/claude-code-session-state"
 import { getAgentDisplayName } from "../../shared/agent-display-names"
 import { createNoSisyphusGptHook } from "./index"
+import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
 
 const SISYPHUS_DISPLAY = getAgentDisplayName("sisyphus")
 const HEPHAESTUS_DISPLAY = getAgentDisplayName("hephaestus")
@@ -22,7 +23,7 @@ function createOutput(): HookOutput {
 }
 
 function createHookContext(showToast: (input: unknown) => Promise<unknown>): PluginInput {
-  return testCoerce<PluginInput>({
+  return unsafeTestValue<PluginInput>({
     client: { tui: { showToast } },
   })
 }