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/domain.py

@@ -0,0 +1,87 @@
+"""Shared domain value objects used across providers, agent tools and the proposal engine.
+
+These are deliberately plain (pydantic) models decoupled from the ORM so that
+SchedulingProvider implementations and the agent can be tested without a database.
+"""
+
+from __future__ import annotations
+
+import enum
+from datetime import datetime
+
+from pydantic import BaseModel, Field
+
+
+class BookingStatus(enum.StrEnum):
+    pending = "pending"
+    resolved_by_owner = "resolved_by_owner"  # owner contacted client directly (primary flow)
+    confirmed = "confirmed"  # owner confirmed a slot → Gogo sends confirmation SMS
+    rejected = "rejected"
+    expired = "expired"
+
+
+class CallOutcome(enum.StrEnum):
+    human_answered = "human_answered"
+    request_created = "request_created"
+    info_only = "info_only"
+    message_taken = "message_taken"
+    abandoned = "abandoned"
+
+
+class ProviderType(enum.StrEnum):
+    google_calendar = "google_calendar"
+    partner_api = "partner_api"
+    mock = "mock"  # in-memory, for tests and demos
+
+
+class Slot(BaseModel):
+    """One concrete offerable time slot (timezone-aware datetimes)."""
+
+    start: datetime
+    end: datetime
+    staff_id: str | None = None
+    staff_name: str | None = None
+
+    def model_post_init(self, __context) -> None:
+        if self.start.tzinfo is None or self.end.tzinfo is None:
+            raise ValueError("Slot datetimes must be timezone-aware")
+
+
+class ServiceInfo(BaseModel):
+    """Service as seen by providers / the agent (decoupled from ORM row)."""
+
+    id: str  # our service UUID as string, or partner service id for catalog sync
+    name: str
+    duration_min: int
+    price_min: float | None = None
+    price_max: float | None = None
+    currency: str = "BAM"
+    home_visit: bool = False
+    agent_note: str | None = None
+    active: bool = True
+
+
+class BookingRequestData(BaseModel):
+    """Payload the proposal engine hands to a provider's deliver_request()."""
+
+    gogo_request_id: str
+    tenant_id: str
+    created_at: datetime
+    source: str  # "voice" | "chat"
+    client_name: str
+    client_phone: str
+    service_id: str | None = None
+    service_name_raw: str = ""
+    requested_slots: list[Slot] = Field(default_factory=list)  # 0-3, ordered by preference
+    time_preference_text: str = ""
+    home_visit: bool = False
+    address: str | None = None
+    summary: str = ""
+    transcript_url: str = ""
+    dry_run: bool = False
+
+
+class DeliveryResult(BaseModel):
+    ok: bool
+    partner_request_id: str | None = None
+    detail: str = ""