feat: SSE para chat desktop, rate limiting, retry, testes e atualizacao de stack

- Implementa Server-Sent Events (SSE) para chat no desktop com fallback HTTP
- Adiciona rate limiting nas APIs de chat (poll, messages, sessions)
- Adiciona retry com backoff exponencial para mutations
- Cria testes para modulo liveChat (20 testes)
- Corrige testes de SMTP (unit tests para extractEnvelopeAddress)
- Adiciona indice by_status_lastActivity para cron de sessoes inativas
- Atualiza stack: Bun 1.3.4, React 19, recharts 3, noble/hashes 2, etc

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

convex/usbPolicy.ts

@@ -1,7 +1,7 @@
 import { v } from "convex/values"
 import { mutation, query } from "./_generated/server"
 import type { Id, Doc } from "./_generated/dataModel"
-import { sha256 } from "@noble/hashes/sha256"
+import { sha256 } from "@noble/hashes/sha2.js"
 
 const DEFAULT_TENANT_ID = "default"