Add Week 5: Literature Search and Review

- New week-05.md page with session description, learning objectives,
  embedded slide deck, blog link, and practicum scaffold notes
- Built Reveal.js slide deck under courses/slides/agentic-research/week-05/
  (presentation.html + assets) covering lit review pipeline, paper cards,
  strand fan-out, synthesis, three defences against AI failure modes
- Update agentic-research index.md to link week-05.md

Author: neuromechanist