contentanalysis 1.0.0

• Improved PDF import module to identify
• Improved plot_citation_clusters(): TF-IDF bar chart now uses a 2-column grid layout with color-coded section title annotations
• Fixed R CMD check NOTE about hidden .claude directory by adding it to .Rbuildignore
• Fixed README: cluster plots are now rendered as static PNG images visible on GitHub
• Fixed README: word distribution plot no longer appears twice