Update stats

backend/app/crud.py

@@ -111,3 +111,24 @@ async def update_session(
     await session.commit()
     await session.refresh(sleep_session)
     return sleep_session
+
+
+async def get_all_time_stats(session: AsyncSession) -> tuple[int, float]:
+    statement = select(func.count(), func.min(SleepSession.start_time))
+    result = await session.exec(statement)
+    total_sessions, first_session_time = result.one()
+
+    if total_sessions == 0 or first_session_time is None:
+        return 0, 0.0
+
+    # DB has naive datetimes
+    first_session_time_naive = first_session_time.replace(tzinfo=None)
+    
+    # Get current date (naive for comparison)
+    today_date = datetime.now().date()
+    first_date = first_session_time_naive.date()
+    
+    num_days = (today_date - first_date).days + 1
+    avg_sleeps = total_sessions / num_days if num_days > 0 else 0.0
+    
+    return total_sessions, avg_sleeps