M1: backend core + proposal engine

- FastAPI skeleton, SQLAlchemy models (§13), Alembic initial migration
- SchedulingProvider interface with google_calendar (free/busy read-only),
  partner_api (Appendix B client) and mock implementations
- Proposal engine: create → provider-routed delivery → owner actions
  (resolve/confirm+SMS/reject) → expiry + reminders (§9)
- Signed single-use action links, .ics METHOD:REQUEST attachment
- Partner outcome webhook with HMAC verification + polling fallback
- SmsProvider (console) with Bosnian templates (§5.5), EmailProvider (console/SMTP)
- Fake partner API server in tests/ — Appendix B reference implementation
- 43 tests: slot math, proposal lifecycle, action links, partner contract

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

gogo/email/sender.py

@@ -0,0 +1,92 @@
+"""EmailProvider interface: SMTP for production, console for dev/tests."""
+
+from __future__ import annotations
+
+import logging
+from dataclasses import dataclass, field
+from email.message import EmailMessage as MimeMessage
+from typing import Protocol
+
+import aiosmtplib
+
+from gogo.config import get_settings
+
+log = logging.getLogger("gogo.email")
+
+
+@dataclass
+class EmailMessage:
+    to: list[str]
+    subject: str
+    text: str
+    html: str | None = None
+    # attachments: (filename, mimetype, bytes)
+    attachments: list[tuple[str, str, bytes]] = field(default_factory=list)
+
+
+class EmailProvider(Protocol):
+    async def send(self, msg: EmailMessage) -> None: ...
+
+
+class ConsoleEmailProvider:
+    """Logs emails instead of sending; keeps them in memory for tests."""
+
+    sent: list[EmailMessage]
+
+    def __init__(self) -> None:
+        self.sent = []
+
+    async def send(self, msg: EmailMessage) -> None:
+        self.sent.append(msg)
+        log.info(
+            "EMAIL to=%s subject=%r attachments=%d\n%s",
+            msg.to,
+            msg.subject,
+            len(msg.attachments),
+            msg.text,
+        )
+
+
+class SmtpEmailProvider:
+    async def send(self, msg: EmailMessage) -> None:
+        s = get_settings()
+        mime = MimeMessage()
+        mime["From"] = s.email_from
+        mime["To"] = ", ".join(msg.to)
+        mime["Subject"] = msg.subject
+        mime.set_content(msg.text)
+        if msg.html:
+            mime.add_alternative(msg.html, subtype="html")
+        for filename, mimetype, data in msg.attachments:
+            maintype, subtype = mimetype.split("/", 1)
+            mime.add_attachment(data, maintype=maintype, subtype=subtype, filename=filename)
+        await aiosmtplib.send(
+            mime,
+            hostname=s.smtp_host,
+            port=s.smtp_port,
+            username=s.smtp_user or None,
+            password=s.smtp_password or None,
+            start_tls=s.smtp_starttls,
+        )
+
+
+_provider: EmailProvider | None = None
+
+
+def get_email_provider() -> EmailProvider:
+    global _provider
+    if _provider is None:
+        _provider = (
+            SmtpEmailProvider() if get_settings().email_provider == "smtp" else ConsoleEmailProvider()
+        )
+    return _provider
+
+
+def set_email_provider(p: EmailProvider | None) -> None:
+    """Test hook."""
+    global _provider
+    _provider = p
+
+
+async def send_email(msg: EmailMessage) -> None:
+    await get_email_provider().send(msg)