Merge 00+01 into single notebook, streamline to 5+2 structure

00_introduction + 01_evaluation merged into 01_evaluation_and_tuning.
Flow: Setup → first call → LLM failures → accuracy → manual tuning
all in one notebook. Normalized cell IDs. Updated README + links.

Structure: 01-05 main path + 2 appendices.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: abossard