fix(tests): revert to working spawn pattern from commit 39ee946

The Proxy approach added unnecessary complexity. The real fix was
ensuring constants.processEnv is a direct reference to process.env
(not a snapshot), which we already have at line 30.

The working pattern from commit 39ee946:
- constants.processEnv = process.env (direct Proxy reference)
- Spawn spreads: {...process.env, ...constants.processEnv, ...spawnEnv}
- VITEST=1 set on actual process.env at module load (lines 23-24)

This preserves Windows Proxy behavior because spreading a Proxy
creates a fresh snapshot each spawn, not a stale object.

Author: jdalton

packages/cli/test/utils.mts

@@ -266,50 +266,13 @@ export async function spawnSocketCli(
   const commandArgs = isJsFile ? [entryPath, ...args] : args
 
   try {
-    // In test mode, use a Proxy to preserve Windows process.env Proxy behavior.
-    // In production, use a static snapshot for performance.
-    const env = process.env['VITEST']
-      ? new Proxy(
-          {},
-          {
-            get(_target, prop) {
-              // Priority: spawnEnv > constants.processEnv
-              if (spawnEnv && prop in spawnEnv) {
-                return spawnEnv[prop]
-              }
-              return constants.processEnv[prop]
-            },
-            ownKeys(_target) {
-              const keys = new Set([
-                ...Object.keys(constants.processEnv),
-                ...(spawnEnv ? Object.keys(spawnEnv) : []),
-              ])
-              return [...keys]
-            },
-            getOwnPropertyDescriptor(_target, prop) {
-              const value =
-                (spawnEnv && prop in spawnEnv
-                  ? spawnEnv[prop]
-                  : constants.processEnv[prop]) ?? undefined
-              return value !== undefined
-                ? {
-                    enumerable: true,
-                    configurable: true,
-                    value,
-                  }
-                : undefined
-            },
-          },
-        )
-      : {
-          ...process.env,
-          ...constants.processEnv,
-          ...spawnEnv,
-        }
-
     const output = await spawn(command, commandArgs, {
       cwd,
-      env,
+      env: {
+        ...process.env,
+        ...constants.processEnv,
+        ...spawnEnv,
+      },
       ...restOptions,
       // Close stdin to prevent tests from hanging
       // when commands wait for input. Must be after restOptions