feat(backend): FastAPI + libSQL + auth register/login/me + tests (TDD)

- FastAPI app with lifespan, CORS, health endpoint
- SQLAlchemy 2.0 async with aiosqlite, Base/UUIDMixin/TenantMixin/TimestampMixin
- Tenant and User models with multi-tenant isolation
- Auth: register (creates tenant+user), login, /me endpoint
- JWT HS256 tokens, bcrypt password hashing
- Alembic async setup with initial migration
- 6 passing tests (register, login, wrong password, me, no token, health)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/db/base.py

@@ -0,0 +1,32 @@
+import uuid
+from datetime import datetime, UTC
+
+from sqlalchemy import String, Text
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
+
+
+def uuid7() -> str:
+    return str(uuid.uuid4())
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+class UUIDMixin:
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=uuid7)
+
+
+class TenantMixin:
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
+
+
+class TimestampMixin:
+    created_at: Mapped[str] = mapped_column(
+        Text, default=lambda: datetime.now(UTC).isoformat()
+    )
+    updated_at: Mapped[str] = mapped_column(
+        Text,
+        default=lambda: datetime.now(UTC).isoformat(),
+        onupdate=lambda: datetime.now(UTC).isoformat(),
+    )

backend/app/db/models/__init__.py

@@ -0,0 +1,4 @@
+from app.db.models.tenant import Tenant
+from app.db.models.user import User
+
+__all__ = ["Tenant", "User"]

backend/app/db/models/tenant.py

@@ -0,0 +1,18 @@
+from sqlalchemy import String, Text
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.base import Base, UUIDMixin, TimestampMixin
+
+
+class Tenant(Base, UUIDMixin, TimestampMixin):
+    __tablename__ = "tenants"
+    nume: Mapped[str] = mapped_column(String(200))
+    cui: Mapped[str | None] = mapped_column(String(20))
+    reg_com: Mapped[str | None] = mapped_column(String(30))
+    adresa: Mapped[str | None] = mapped_column(Text)
+    telefon: Mapped[str | None] = mapped_column(String(20))
+    email: Mapped[str | None] = mapped_column(String(200))
+    iban: Mapped[str | None] = mapped_column(String(34))
+    banca: Mapped[str | None] = mapped_column(String(100))
+    plan: Mapped[str] = mapped_column(String(20), default="trial")
+    trial_expires_at: Mapped[str | None] = mapped_column(Text)

backend/app/db/models/user.py

@@ -0,0 +1,13 @@
+from sqlalchemy import Boolean, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.base import Base, UUIDMixin, TenantMixin, TimestampMixin
+
+
+class User(Base, UUIDMixin, TenantMixin, TimestampMixin):
+    __tablename__ = "users"
+    email: Mapped[str] = mapped_column(String(200), unique=True, index=True)
+    password_hash: Mapped[str] = mapped_column(String(200))
+    nume: Mapped[str] = mapped_column(String(200))
+    rol: Mapped[str] = mapped_column(String(20), default="owner")
+    activ: Mapped[bool] = mapped_column(Boolean, default=True)

backend/app/db/session.py

@@ -0,0 +1,11 @@
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+from app.config import settings
+
+engine = create_async_engine(settings.DATABASE_URL, echo=False)
+AsyncSessionLocal = async_sessionmaker(engine, expire_on_commit=False)
+
+
+async def get_db():
+    async with AsyncSessionLocal() as session:
+        yield session