[D10] validation.ipynb: Cells 4-5 + Full Run ✅ CHECKPOINT 2

[Siddardth7]

Due: April 5 | Day 10 of 14 — CHECKPOINT

• Cell 4: Side-by-side bar chart: CLT vs FEA deflection + σₓₓ with % error annotated on bars (Matplotlib)
• Cell 5: Grouped bar chart: Tsai-Wu vs Hashin FT/FC/MT/MC failure indices per ply (all on same figure)
• CHECKPOINT REVIEW: Kernel → Restart & Run All — all 5 cells complete, all charts visible
• Save notebook with outputs committed (don't clear before committing)
• Push clean commit tagged v0.9-notebook-complete

✅ Done when: Full notebook runs clean top-to-bottom. All charts display inline.