feat: allow pass hostname in docker env

[tomerqodo]

Benchmark PR from agentic-review-benchmarks#6

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Note

Introduces configurable SMTP HELO/EHLO hostname for deployments behind NAT or with strict MTAs.

• Adds SMTP_LOCAL_HOSTNAME to config (MailConfig) and wires it into SMTPClient as local_hostname for smtplib.SMTP/SMTP_SSL and EHLO during STARTTLS
• Updates .env.example files (api, integration tests, docker) and docker-compose.yaml to expose SMTP_LOCAL_HOSTNAME
• Refactors SMTPClient.send to select SMTP vs SMTP_SSL via a ternary and to EHLO with the configured hostname when using STARTTLS
• Adjusts unit tests to expect local_hostname to be passed (uses ANY)

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EHLO behavior changed from server to local hostname

Medium Severity

The SMTP EHLO command behavior changed unintentionally. Previously, smtp.ehlo(self.server) used the SMTP server's address for the EHLO domain name (as documented in the removed comment). Now smtp.ehlo(local_host) uses SMTP_LOCAL_HOSTNAME if configured, otherwise an empty string which causes Python's smtplib to use socket.getfqdn() (the local machine's FQDN). This silent change in default behavior could break existing opportunistic TLS SMTP configurations that relied on using the server address for EHLO.

Additional Locations (1)

• api/libs/smtp.py#L24-L25