fix(ci): skip e2e-brev tests when secrets are not available

The e2e-brev vitest project was running during normal test-unit CI
which lacks Brev secrets. Use describe.runIf and vitest enabled flag
to skip gracefully when BREV_API_TOKEN is not set.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jyaunches

test/e2e/brev-e2e.test.js

@@ -106,12 +106,11 @@ function runRemoteTest(scriptPath) {
 
 // --- suite ------------------------------------------------------------------
 
-describe("Brev E2E", () => {
+const REQUIRED_VARS = ["BREV_API_TOKEN", "NVIDIA_API_KEY", "GITHUB_TOKEN", "INSTANCE_NAME"];
+const hasRequiredVars = REQUIRED_VARS.every((key) => process.env[key]);
+
+describe.runIf(hasRequiredVars)("Brev E2E", () => {
   beforeAll(() => {
-    // Validate required env vars up front
-    for (const key of ["BREV_API_TOKEN", "NVIDIA_API_KEY", "GITHUB_TOKEN", "INSTANCE_NAME"]) {
-      if (!process.env[key]) throw new Error(`${key} not set`);
-    }
 
     // Authenticate with Brev
     mkdirSync(path.join(homedir(), ".brev"), { recursive: true });