Fix GitHub workflow to properly activate virtual environment

- Combine venv setup and tito execution in same step
- Add pytest installation for tito environment validation
- Add explanatory comments about GitHub Actions shell behavior
- Remove environment skipping hack in favor of proper setup
- Workflow now uses tito CLI consistently for book generation

.github/workflows/deploy-book.yml

@@ -1,6 +1,7 @@
-name: Deploy TinyTorch Jupyter Book (Streamlined)
+name: Deploy TinyTorch Jupyter Book (Streamlined with tito)
 
 # Trigger the workflow on push to main branch (publishing) or manual dispatch
+# This workflow uses tito CLI for consistent book generation and building
 on:
   push:
     branches: [ main ]
@@ -48,10 +49,17 @@ jobs:
         pip install --upgrade pip
         pip install jupyter-book jupytext
         pip install -r book/requirements.txt
+        pip install -r requirements.txt  # Install main project dependencies
         pip install -e .  # Install tito CLI
         
     - name: Generate content and build book
       run: |
+        # Set up virtual environment and run tito in same step
+        # Note: Each GitHub Actions step runs in a separate shell,
+        # so we need to activate the venv in the same step as tito
+        python -m venv .venv
+        source .venv/bin/activate
+        pip install pytest  # Install missing dependency for tito environment checks
         # Use tito to generate content and build book
         tito book build