chore(email): decommission SMTP2GO references — local MTA only

SMTP2GO is no longer used: Listmonk relays through the local Postfix MTA
(172.18.0.1:25 from the Docker network), which DKIM-signs and delivers
direct-to-recipient-MX; transactional mail goes through Carbonio. Verified
zero smtp2go in any live container env + postfix has no external relayhost.

Removed the stale references so a rebuild/new dev can't re-introduce it:
- api/src/config.ts: SMTP_HOST default mail.smtp2go.com -> co.carrierone.com
- scripts/workers/crypto_payment_worker.py: same default fix
- infra/ansible all.yml: listmonk_smtp_* now 172.18.0.1:25, no auth (+comment)
- app.env.j2 / email.ts / crm.md / go-live-todo.md / architecture.svg: docs

docs/architecture.svg

@@ -165,7 +165,7 @@
   <rect x="487" y="524" width="72" height="18" rx="3" fill="#fed7aa" stroke="#f97316"/>
   <text x="523" y="537" text-anchor="middle" font-size="8" fill="#9a3412">Anytime MB</text>
   <rect x="564" y="524" width="72" height="18" rx="3" fill="#e0f2fe" stroke="#7dd3fc"/>
-  <text x="600" y="537" text-anchor="middle" font-size="8" fill="#0c4a6e">SMTP2GO</text>
+  <text x="600" y="537" text-anchor="middle" font-size="8" fill="#0c4a6e">Local MTA</text>
   <rect x="641" y="524" width="72" height="18" rx="3" fill="#f1f5f9" stroke="#cbd5e1"/>
   <text x="677" y="537" text-anchor="middle" font-size="8" fill="#475569">TronGrid</text>