Initial commit: habit tracker PWA with Google OAuth, push notifications

FastAPI + SQLAlchemy/Alembic + MariaDB backend with Jinja2/htmx/Alpine
server-rendered frontend. Multi-user via Google OAuth, daily habit
tracking, monthly/weekly history views, Web Push reminders via
APScheduler, and PWA support (manifest, service worker, offline caching).

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

app/models/habit.py

@@ -0,0 +1,48 @@
+import enum
+from datetime import datetime, time
+
+from sqlalchemy import Enum, ForeignKey, Integer, SmallInteger, String, Time
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+ALL_WEEKDAYS_MASK = 0b1111111  # 월~일 전부 (bit0=월 ... bit6=일)
+
+
+class HabitType(str, enum.Enum):
+    BUILD = "build"  # 만들고 싶은 습관
+    QUIT = "quit"  # 멈추고 싶은 습관
+
+
+class HabitStatus(str, enum.Enum):
+    ACTIVE = "active"
+    COMPLETED = "completed"
+
+
+class Habit(Base):
+    __tablename__ = "habit"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    user_id: Mapped[int | None] = mapped_column(
+        ForeignKey("user.id", ondelete="CASCADE"), nullable=True
+    )
+    name: Mapped[str] = mapped_column(String(200), nullable=False)
+    habit_type: Mapped[HabitType] = mapped_column(Enum(HabitType, native_enum=False, length=20), nullable=False)
+    status: Mapped[HabitStatus] = mapped_column(
+        Enum(HabitStatus, native_enum=False, length=20), nullable=False, default=HabitStatus.ACTIVE
+    )
+    weekdays_mask: Mapped[int] = mapped_column(SmallInteger, nullable=False, default=ALL_WEEKDAYS_MASK)
+    condition_text: Mapped[str | None] = mapped_column(String(300), nullable=True)
+    reminder_time: Mapped[time | None] = mapped_column(Time, nullable=True)
+    sort_order: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(server_default=func.now(), nullable=False)
+    completed_at: Mapped[datetime | None] = mapped_column(nullable=True)
+
+    logs: Mapped[list["HabitLog"]] = relationship(
+        back_populates="habit", cascade="all, delete-orphan", passive_deletes=True
+    )
+
+    def is_scheduled_on(self, weekday: int) -> bool:
+        """weekday: Python date.weekday() 기준 (월=0 ... 일=6)"""
+        return bool(self.weekdays_mask & (1 << weekday))