test(doctor): isolate loaded version module import

Load the doctor loaded-version module through a unique test-only specifier so Bun module mocks from system tests cannot leak into the real module assertions in CI.

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

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

src/cli/doctor/checks/system-loaded-version.test.ts

@@ -4,7 +4,11 @@ import { tmpdir } from "node:os"
 import { dirname, join } from "node:path"
 
 import { PACKAGE_NAME } from "../constants"
-import { getLoadedPluginVersion, getSuggestedInstallTag } from "./system-loaded-version"
+
+const systemLoadedVersionModulePath = "./system-loaded-version?system-loaded-version-test"
+
+const { getLoadedPluginVersion, getSuggestedInstallTag }: typeof import("./system-loaded-version") =
+  await import(systemLoadedVersionModulePath)
 
 const originalOpencodeConfigDir = process.env.OPENCODE_CONFIG_DIR
 const originalXdgCacheHome = process.env.XDG_CACHE_HOME