test(e2e): isolate sync option-routing children from ambient NODE_OPTIONS (#109)

The runCli helper spread process.env into the spawned CLI, so a shell whose
NODE_OPTIONS makes node print a startup warning polluted stderr ahead of the
JSON error envelope and broke JSON.parse in the --format json assertion.
Reproduced with NODE_OPTIONS='--require <emit-warning script>': 1 failed /
19 passed before, 20/20 after. The child now drops NODE_OPTIONS and sets
NODE_NO_WARNINGS, matching cli-cache-degraded's handling.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: sjsyrek

tests/e2e/cli-sync-option-routing.e2e.test.ts

@@ -78,6 +78,10 @@ describe('CLI sync option routing E2E', () => {
         DEEPL_API_KEY: 'mock-api-key-for-testing:fx',
         NO_COLOR: '1',
         CI: undefined,
+        // Ambient NODE_OPTIONS can make node print warnings to stderr, which
+        // the JSON-envelope assertions parse.
+        NODE_OPTIONS: undefined,
+        NODE_NO_WARNINGS: '1',
       },
       stdio: ['ignore', 'pipe', 'pipe'],
       timeout: 15000,