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/tools/lsp/client.test.ts

@@ -16,6 +16,7 @@ afterAll(() => { mock.restore() })
 
 import { LSPClient, lspManager, validateCwd } from "./client"
 import type { ResolvedServer } from "./types"
+import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
 
 describe("LSPClient", () => {
   beforeEach(async () => {
@@ -36,7 +37,7 @@ describe("LSPClient", () => {
       const originalSetTimeout = globalThis.setTimeout
       globalThis.setTimeout = ((fn: (...args: unknown[]) => void, _ms?: number) => {
         fn()
-        return testCoerce<ReturnType<typeof setTimeout>>(0)
+        return unsafeTestValue<ReturnType<typeof setTimeout>>(0)
       }) as typeof setTimeout
 
       const server: ResolvedServer = {
@@ -50,7 +51,7 @@ describe("LSPClient", () => {
 
       // Stub protocol output: we only want to assert notifications.
       const sendNotificationSpy = spyOn(
-        testCoerce<{ sendNotification: (m: string, p?: unknown) => void }>(client),
+        unsafeTestValue<{ sendNotification: (m: string, p?: unknown) => void }>(client),
         "sendNotification"
       )