fix(wechat): stop relay bootstrap from hijacking LLM provider selection.

Schedule LLM now binds an explicit provider key and fails closed on network errors so dead relay endpoints cannot block ordinary chat; relay bootstrap is opt-in only.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/portal-agent-services-bootstrap.test.mjs

@@ -367,6 +367,10 @@ test('falls back from PG experience and degrades invalid image config', async ()
 
 test('keeps disabled experience null and reports background LLM failures', async () => {
   const setup = createSetup({
+    env: {
+      EXPERIENCE_PG_URL: 'postgres://experience',
+      H5_RELAY_BOOTSTRAP_DISABLED: '0',
+    },
     runtime: {
       experienceEnabled: false,
       agentWorker: { enabled: false },