Add unified report generator for analysis results

Consolidates all sweep results into publication-ready tables:
- CSV format for data analysis and plotting
- Markdown format for documentation and GitHub
- LaTeX booktabs format for manuscript inclusion

Features:
- Auto-loads latest result files from results/analysis/
- Supports 5 sweep types: xi, materials, curvature vs B/R/precision
- CLI with --format, --output, --all, --results-dir options
- Generates organized output in results/reports/

Functions:
- load_latest_results(): Glob-based discovery of timestamped JSONs
- generate_csv_*(): CSV export for all sweep types
- generate_markdown_table(): GitHub-flavored Markdown tables
- generate_latex_table(): Publication-quality LaTeX tables

Usage:
  python generate_report.py --all
  python generate_report.py --format markdown --output report.md
  python generate_report.py --format latex --output tables.tex

Output examples:
- CSV: results/reports/csv/{xi_sweep,materials,curvature_vs_{B,R,precision}}.csv
- Markdown: results/reports/analysis_report.md (5 sections, all sweeps)
- LaTeX: results/reports/analysis_tables.tex (ready for \input in manuscript)

Completes Task 9 from TODO list.

Author: arcticoder