feat: P4.6 agent demo + escalate button + support seed/smoke (P4 complete)

apps/agent-demo (Vite): agent sets AVAILABLE, sees assigned tickets, opens the
thread, replies. message-demo customer pane gains 'escalate to support' (via
SupportProvider/useEscalate). seed-support + smoke-support prove the loop:
escalate -> auto-assign -> agent reply -> customer receives. 45 tests; realtime/
inbox/support smokes all pass; both demos build.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/agent-demo/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "lib": ["ES2022", "DOM"],
+    "jsx": "react-jsx",
+    "types": ["react", "react-dom"],
+    "noEmit": true
+  },
+  "include": ["src/**/*.ts", "src/**/*.tsx"]
+}