feat(HJ): Chapter 3 — Advanced Analytical Mechanics (Hamilton-Jacobi)

Add Chapter 3 with 13 concept files covering:
- HJ Fundamentals: derivation, separation, action-angle, EM coupling
- Mechanics problems: free particle, projectile, SHO, Kepler, rigid rotator
- EM problems: uniform E-field, cyclotron, E×B drift, Coulomb

Also: manifest update (13 entries), macro additions (HJ + \bm + \dd override),
unicode cleanup, compilation fixes.

ap-physics-c-handbook.tex

@@ -20,4 +20,7 @@
 \part{Electricity \& Magnetism}
 \input{chapters/em}
 
+\part{Advanced Topics}
+\input{chapters/advanced}
+
 \end{document}