Add create_draft tool and allow_send toggle per account

- create_draft: saves email as draft in IMAP Drafts folder
- allow_send: global config toggle (default true), overridable per account
- When sending disabled, send_email returns error suggesting create_draft

config.example.yml

@@ -7,6 +7,10 @@ poke_api_key: "your-api-key-here"
 # MCP_API_KEY is set via environment variable (not in this file)
 # It secures the MCP server so only you can use it
 
+# Global send toggle — set to false to disable send_email for all accounts
+# Agents can still use create_draft. Override per account with allow_send.
+allow_send: true
+
 accounts:
   # Minimal — SMTP falls back to IMAP host/credentials
   - id: personal