Merge upstream/main: resolved conflicts keeping fork's changes

Merged upstream (e31386a) into fork with conflict resolution strategy:
- Kept all fork's changes (--ours) for conflicting files
- Text files: CI workflow, gitignore, README, scripts, code
- Binary files: PDFs, pkl files
- Paper files: main.tex, custom.bib

Fork changes preserved:
- Text classification implementation (issue #33)
- Enhanced statistical analysis with LaTeX output
- Adaptive t-test thresholds with bootstrap CI
- Grouped classification accuracy bar chart
- All 40 classification figures
- CI dependency fixes (wordcloud, nltk)

Upstream changes (if any) that don't conflict are auto-merged.

PR #34 will auto-update with this merge.

Author: jeremymanning