Standardize categories and tags across posts

[streamcode9]

Summary

• Added missing tags and consolidated categories for remaining posts, e.g., moved anime and cinema under the art category with dedicated tags.
• Grouped biographies under a shared history category and tagged individual figures like Karl Marx and Ivan Pavlov.
• Introduced broader categories such as technology, sports, and productivity while tagging specific topics.

Testing

• gem install bundler jekyll (fails: 403 "Forbidden")
• bundle exec jekyll build (fails: Could not locate Gemfile or .bundle/ directory)
• jekyll build (fails: command not found: jekyll)

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https://chatgpt.com/codex/tasks/task_e_689910d2e6a4833287a63e70439533d9