add list of core components

.github/copilot-instructions.md

@@ -7,6 +7,14 @@ Excel → PDF converter for German attendance lists. Reads attendance data from
 
 ### Core Components
 ```
+generate.py              # CLI entry point (Click-based)
+src/config_loader.py     # Loads config.json and schema.json
+src/excel_reader.py      # Reads attendance data from Excel file
+src/models.py            # Data models (participant, month, days)
+src/validators.py        # Validation logic for Excel input data
+src/pdf_filler.py        # Fills PDF form fields from model data
+src/exceptions.py        # Custom exceptions for the entire pipeline
+```
 
 ### PDF Structure (Form Fields)
 - `person.name`: Person's full name