Add analyze-benchmarks command for pytest-benchmark visualization

[tschm]

Adds a new command to analyze and visualize pytest-benchmark results:

• Reads benchmarks.json produced by pytest-benchmark
• Prints sorted table with benchmark names, mean milliseconds, and OPS
• Generates interactive Plotly bar chart visualization
• Saves HTML report for sharing results
• Gracefully handles missing or invalid benchmark files

The command requires pandas and plotly from the dev dependency group.

Usage:
rhiza-tools analyze-benchmarks
rhiza-tools analyze-benchmarks --benchmarks-json path/to/benchmarks.json