Auto-compute rote calculation answers

Compute and auto-fill rote calculation answers

Escaping rote algebra after conceptual understanding is locked in via /learn

• · week number
• · question number
• · optional conceptual setup note

• · derivation chain with intermediate steps
• · final answer inserted into README
• · confirmation message

• · pdf_reader.py script
• · week-answer-fill skill

• · user has completed /learn session
• · WeekN/ folder and README exist
• · question slot in README is empty

• · answer slot already filled
• · PDF parse fails
• · missing exercise.md
• · question text is conceptual not computational

• · guards against already-filled answers
• · anchors on user's prior framing from stuck.md
• · uses Unicode math in chat and LaTeX in file