feat: Add consistent 'Where This Code Lives' template across modules

- Add template section to tensor, layers, activations, and cnn modules
- Create docs/development/module-template.md for future reference
- Clarify learning vs building structure consistently
- Show students where their code will live in the final package
- Decouple learning modules from production organization

docs/development/module-template.md

@@ -0,0 +1,55 @@
+# Module Template: "Where This Code Lives" Section
+
+## 📦 Where This Code Lives in the Final Package
+
+**Learning Side:** You work in `modules/{module_name}/{module_name}_dev.py`  
+**Building Side:** Code exports to `tinytorch.core.{destination}`
+
+```python
+# Final package structure:
+from tinytorch.core.{destination} import {exported_classes}
+from tinytorch.core.tensor import Tensor
+```
+
+**Why this matters:**
+- **Learning:** Focused modules for deep understanding
+- **Production:** Proper organization like industry frameworks
+- **Consistency:** Related functionality grouped together
+
+## Template Variables
+
+Replace these placeholders in each module:
+
+- `{module_name}`: The module directory name (e.g., "tensor", "layers", "cnn")
+- `{destination}`: Where the code exports in the final package (e.g., "tensor", "layers", "activations")
+- `{exported_classes}`: The main classes/functions being exported (e.g., "Tensor", "Dense, Conv2D", "ReLU, Sigmoid")
+
+## Examples
+
+### Tensor Module
+```python
+# Learning Side: modules/tensor/tensor_dev.py
+# Building Side: tinytorch.core.tensor
+from tinytorch.core.tensor import Tensor
+```
+
+### Layers Module  
+```python
+# Learning Side: modules/layers/layers_dev.py
+# Building Side: tinytorch.core.layers
+from tinytorch.core.layers import Dense, Conv2D
+```
+
+### CNN Module
+```python
+# Learning Side: modules/cnn/cnn_dev.py
+# Building Side: tinytorch.core.layers (Conv2D lives with Dense)
+from tinytorch.core.layers import Dense, Conv2D
+```
+
+## Usage Instructions
+
+1. Copy this template section into each module's `*_dev.py` file
+2. Replace the template variables with module-specific values
+3. Update the `#| default_exp` directive to match the destination
+4. Ensure the exported classes match what's actually being exported