feat: ChatGPT Custom GPT support in chat bot + sqcp SMTP routing fix

- chat.ts: system prompt now includes step-by-step ChatGPT Custom GPT
  setup (openapi.json import + OAuth), Claude/Cursor/Windsurf config,
  and mortgage broker guidance — bot no longer incorrectly says ChatGPT
  is unsupported
- smtp.ts: all sqcp_* accounts now route to mail.squaremcp.com (SQCP_SMTP_HOST)
  instead of the fetcherpay server
- tools.ts: ACCOUNT_PARAM description now lists all 14 mailboxes including
  the 7 squaremcp.com accounts so Claude picks the right one without guessing
- package.json: postinstall hook runs imapflow patch script after npm install
- hermes-k8s.yaml: updated image digest to current production build

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/chat.ts

@@ -10,16 +10,54 @@ You have real tools connected to live platforms. When a visitor asks "can it sen
 What SquareMCP does:
 - Connects AI coding assistants to social platforms: LinkedIn, TikTok, WhatsApp, Instagram, Twitter/X, Facebook, Telegram, Discord, Slack, and Email
 - Works with any MCP-compatible client: Claude Desktop, Claude Code, Cursor, Windsurf, opencode, Codex CLI
+- Also works with ChatGPT via Custom GPT (uses the REST API + OAuth, not MCP protocol directly)
 - Provides a multi-tenant SaaS platform where each customer securely stores their own platform credentials
 - Plans: Free (100 calls/month), Pro, Business
 
+How to connect — by AI client:
+
+CHATGPT (chatgpt.com):
+SquareMCP works with ChatGPT via a Custom GPT with Actions. Steps:
+1. Go to chatgpt.com → Explore GPTs → Create → Actions → Import from URL
+2. Import the OpenAPI schema: https://hermes.squaremcp.com/openapi.json
+3. Set Authentication to OAuth:
+   - Authorization URL: https://hermes.squaremcp.com/oauth/authorize
+   - Token URL: https://hermes.squaremcp.com/oauth/token
+   - Register your OAuth client first at: https://hermes.squaremcp.com/oauth/register
+4. Connect your social accounts in the SquareMCP dashboard at https://app.squaremcp.com
+5. Ask your Custom GPT: "Send a WhatsApp to my top 3 clients" — it just works.
+Full guide: email support@squaremcp.com for the ChatGPT setup walkthrough.
+
+CLAUDE (claude.ai or Claude Desktop):
+1. In claude.ai → Settings → Integrations → Add MCP server
+2. Server URL: https://hermes.squaremcp.com/mcp
+3. Authenticate via OAuth
+4. Connect social accounts at https://app.squaremcp.com
+
+CURSOR / WINDSURF / CODEX CLI / opencode:
+Add to your MCP config:
+{
+  "mcpServers": {
+    "squaremcp": {
+      "url": "https://hermes.squaremcp.com/mcp",
+      "apiKey": "your-api-key-from-dashboard"
+    }
+  }
+}
+
+For mortgage brokers specifically:
+- ChatGPT Custom GPT is often the easiest starting point — no install required, works in the browser
+- WhatsApp rate blast: one command sends updates to hundreds of clients
+- Multi-channel: handle WhatsApp, email, LinkedIn, and Facebook from a single AI conversation
+- Compliance: we can scope the setup to stay within RESPA/TILA guidelines
+
 When using tools:
 - For demo sends (Slack, Telegram, Discord), send a short, friendly message that explains this is a live SquareMCP demo
 - After a tool succeeds, explain what just happened and how easy it was
 - If a tool fails (missing credentials), explain what credential the customer would set up instead
 - Never expose tokens or internal IDs in your reply
 
-Keep replies concise. If you don't know something, say so and suggest emailing support@squaremcp.com.`;
+Keep replies concise and practical. If you don't know something, say so and suggest emailing support@squaremcp.com.`;
 
 // Tools the public demo agent is allowed to use (no customer auth needed — uses env var creds)
 const DEMO_TOOL_NAMES = new Set([