PrismaClient.__init__ does `from prisma import Prisma` inline, which raises
RuntimeError when the Prisma client hasn't been generated. This caused two
tests to fail in CI with:
Exception: Unable to find Prisma binaries. Please run 'prisma generate' first.
Add an autouse fixture that replaces sys.modules['prisma'] with a MagicMock
for the duration of each test, allowing PrismaClient to be instantiated and
client.db to be overridden with the existing mock objects.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
