feat(03-03): add update_models and delete_project to service

Add update_project_models(project_id, models) and delete_project(project_id)
functions to complete the project service CRUD operations.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/moai/core/services/project.py

@@ -69,3 +69,48 @@ async def get_project_by_name(name: str) -> Project | None:
     async with get_session() as session:
         result = await session.execute(select(Project).where(Project.name.ilike(name)))
         return result.scalar_one_or_none()
+
+
+async def update_project_models(project_id: str, models: list[str]) -> Project | None:
+    """Update a project's models list.
+
+    Args:
+        project_id: The project's UUID.
+        models: List of AI model identifiers.
+
+    Returns:
+        The updated Project object if found, None otherwise.
+    """
+    async with get_session() as session:
+        result = await session.execute(select(Project).where(Project.id == project_id))
+        project = result.scalar_one_or_none()
+
+        if project is None:
+            return None
+
+        project.models = models
+        await session.flush()
+        await session.refresh(project)
+        return project
+
+
+async def delete_project(project_id: str) -> bool:
+    """Delete a project by ID.
+
+    Cascade delete will handle discussions/rounds/messages via SQLAlchemy relationship config.
+
+    Args:
+        project_id: The project's UUID.
+
+    Returns:
+        True if deleted, False if not found.
+    """
+    async with get_session() as session:
+        result = await session.execute(select(Project).where(Project.id == project_id))
+        project = result.scalar_one_or_none()
+
+        if project is None:
+            return False
+
+        await session.delete(project)
+        return True