Fix remaining import issues in notebooks

- Fixed 'from redis_context_course.memory_client import MemoryClient'
  to 'from redis_context_course import MemoryClient'
- Fixed MemoryClient initialization in section-1 notebooks to use MemoryClientConfig
- Section-1 notebooks now pass locally (25/25)

All notebooks now import correctly and use proper API initialization.

Author: abrookins

python-recipes/context-engineering/notebooks/section-1-introduction/01_what_is_context_engineering.ipynb

@@ -192,7 +192,7 @@
       "source": [
         "# Import the Redis Context Course components\n",
         "from redis_context_course.models import Course, StudentProfile, DifficultyLevel, CourseFormat\n",
-        "from redis_context_course.memory_client import MemoryClient\n",
+        "from redis_context_course import MemoryClient\n",
         "from redis_context_course.course_manager import CourseManager\n",
         "from redis_context_course.redis_config import redis_config\n",
         "\n",