fix/analysis cross language

[leo-gan]

Title: Remove cross-language analysis and clean up documentation structure

Summary:
This PR removes all cross-language comparison features and eliminates orphaned documentation files. The benchmark now focuses exclusively on same-language serializer comparisons (C# vs C#, Python vs Python).

Changes:

Code Changes:

• analysis/src/benchmark_analysis/reports.py: Removed cross-language data preparation, multidimensional analysis sections, and cross-language comparison tables from both Markdown and HTML report generators
• Changed HTML dashboard subtitle from "Cross-language serialization performance comparison" to "Serialization performance comparison"
• Regenerated docs/analysis/BENCHMARK_SUMMARY.md and dashboard to contain only pivot tables

Documentation Cleanup:

• Removed docs/_config.yml (Jekyll config - project uses MkDocs)
• Removed orphaned docs/*.md files: benchmark-results.md, getting-started.md, methodology.md
• Removed duplicate analysis/docs/ folder (outdated copies)
• Removed analysis/reports/ folder (generated outputs now only in docs/analysis/)
• Updated docs/analysis/ANALYSIS_METHODOLOGY.md: Removed "Multidimensional Analysis" and "Cross-Language" sections
• Updated docs/analysis/serialization_categories.md: Made observations language-neutral

Result:

• Cleaner codebase focused on per-language analysis
• Single source of truth for documentation in docs/
• MkDocs site builds without orphaned pages

[gemini-code-assist]

Code Review

This pull request streamlines the benchmark reporting system by removing detailed per-language tables, top performer comparisons, and multidimensional analysis from both the generated Markdown summaries and the HTML dashboard. It also simplifies the documentation by removing several files, including the Jekyll configuration and references to the Jupyter notebook. Feedback indicates that the methodology documentation should still describe the HTML dashboard features since they are still being generated, and identifies a typo and a spacing issue in the updated documentation files.