Set up the project skeleton (MIL-001)

pyproject.toml (Python >=3.13, no runtime dependencies, pytest as dev extra),
Python .gitignore, .env.example, constants.py, assignment data files,
Doxyfile and a smoke test.

Task: MIL-001#1
Task: MIL-001#2
Task: MIL-001#3
Task: MIL-001#4
Refs #2
Refs #3
Refs #4
Refs #5

birthdays.csv

@@ -0,0 +1,5 @@
+name,email,year,month,day
+Alice Example,alice@example.com,1990,3,14
+Bob Example,bob@example.com,1985,10,17
+Carol Example,carol@example.com,2001,10,17
+Dave Example,dave@example.com,1978,12,24