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/hours.py

@@ -0,0 +1,79 @@
+"""Working-hours helpers.
+
+Working hours are stored per tenant as:
+    {"mon": [["09:00", "13:00"], ["14:00", "18:00"]], ..., "sun": []}
+Multiple intervals per day model lunch breaks. Missing/empty day = closed.
+All computations happen in the tenant's timezone.
+"""
+
+from __future__ import annotations
+
+from datetime import date, datetime, time, timedelta
+from zoneinfo import ZoneInfo
+
+WEEKDAY_KEYS = ["mon", "tue", "wed", "thu", "fri", "sat", "sun"]
+
+# Bosnian day names (Latin) for UI / agent context
+DAY_NAMES_BS = {
+    "mon": "ponedjeljak",
+    "tue": "utorak",
+    "wed": "srijeda",
+    "thu": "četvrtak",
+    "fri": "petak",
+    "sat": "subota",
+    "sun": "nedjelja",
+}
+
+DEFAULT_WORKING_HOURS: dict[str, list[list[str]]] = {
+    "mon": [["09:00", "18:00"]],
+    "tue": [["09:00", "18:00"]],
+    "wed": [["09:00", "18:00"]],
+    "thu": [["09:00", "18:00"]],
+    "fri": [["09:00", "18:00"]],
+    "sat": [["09:00", "14:00"]],
+    "sun": [],
+}
+
+
+def _parse_hhmm(s: str) -> time:
+    h, m = s.split(":")
+    return time(int(h), int(m))
+
+
+def day_intervals(
+    working_hours: dict, day: date, tz: ZoneInfo
+) -> list[tuple[datetime, datetime]]:
+    """Open intervals for a calendar day as tz-aware datetimes."""
+    key = WEEKDAY_KEYS[day.weekday()]
+    out = []
+    for start_s, end_s in working_hours.get(key, []):
+        start = datetime.combine(day, _parse_hhmm(start_s), tzinfo=tz)
+        end = datetime.combine(day, _parse_hhmm(end_s), tzinfo=tz)
+        if end > start:
+            out.append((start, end))
+    return out
+
+
+def is_open_at(working_hours: dict, at: datetime, tz: ZoneInfo) -> bool:
+    at = at.astimezone(tz)
+    return any(s <= at < e for s, e in day_intervals(working_hours, at.date(), tz))
+
+
+def hours_summary_bs(working_hours: dict) -> str:
+    """Human-readable Bosnian working-hours summary for prompts/emails."""
+    parts = []
+    for key in WEEKDAY_KEYS:
+        intervals = working_hours.get(key, [])
+        if not intervals:
+            parts.append(f"{DAY_NAMES_BS[key]}: zatvoreno")
+        else:
+            spans = ", ".join(f"{a}–{b}" for a, b in intervals)
+            parts.append(f"{DAY_NAMES_BS[key]}: {spans}")
+    return "; ".join(parts)
+
+
+def iter_days(start: date, end: date):
+    d = start
+    while d <= end:
+        yield d
+        d += timedelta(days=1)