Add reproducible Privacy Guard latency analysis

[johnnygreco]

Summary

• add a sanitized dataset of 96 Privacy Guard latency observations with prompt-token and aggregate entity counts
• add a dependency-free, deterministic SVG renderer with a single fitted curve, entity-count color scale, and light/dark theme support
• commit the generated latency-versus-prompt-size figure

Why

This preserves the proof-of-concept analysis as a reproducible artifact that a
dedicated documentation and Dev Note PR can consume later without copying data
or plotting logic.

Impact

This PR changes no Privacy Guard runtime behavior and does not add the figure to
a documentation page. It contains only the analysis bundle and generated SVG.

Validation

• uv run ruff check analysis/render_latency_plot.py
• uv run ruff format --check analysis/render_latency_plot.py
• uv run ty check analysis/render_latency_plot.py
• uv run python analysis/render_latency_plot.py --check
• verified the sanitized CSV contains no email or customer-ID strings
• visually verified the embedded SVG in light and dark color schemes

[github-actions]

Documentation preview

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