Update BrowserCode model comparison plot

[Alezander9]

What

Resyncs official_plots/browser_harness_by_model_{light,dark}.png (the
"Comparing Models for BrowserCode" plot) from
benchmark-x-laminar@45b563b.

The committed copies were generated 2026-06-17 and are the stalest published
copy of this plot anywhere. They still show glm-5.1 (79.7%) as the top
open-weight model and predate every model added since:

• Added: claude-opus-5 (87.0%), claude-fable-5 (87.0%), grok-4.5 (86.3%), kimi-k3 (86.0%), gpt-5.6-sol (84.0%), gpt-5.6-luna xhigh (82.0%) / default (72.4%), gpt-5.6-terra (72.0%), qwen3.8-max (79.0%), minimax-m3 (74.0%), deepseek-v4-flash-0731 (76.0%)
• Dropped: mimo-v2.5/-pro, glm-4.7, glm-5.1, kimi-k2.6, qwen3.6-plus, grok-4.3, gpt-5.4-mini, claude-sonnet-4-6, base deepseek-v4-flash
• Open-weight bars changed from a solid blue fill to a gray fill with a blue dashed outline

Image-only change. generate_plots.py in this repo produces accuracy_by_model
and accuracy_vs_throughput; the three BU Bench plots in the README are
imported copies from benchmark-x-laminar, so nothing here regenerates them.

Companion PR for the same plot in the BrowserCode README: browser-use/browsercode#143

Not in this PR

browser_use_framework_by_model_{light,dark}.png has also drifted from
upstream, which now has two extra bars (qwen3.627b 29.0%, glm-5.1 25.0%);
the top eight are unchanged. Left out because it is a browser-use-framework
plot and unaffected by the BrowserCode results this PR propagates -- say the
word and I will fold it in.

best_of_frameworks_public_dark.png differs from upstream only in PNG
metadata; the rendered content is byte-identical to the light version's
content. Not worth a churn commit.

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Summary by cubic

Refreshes the BrowserCode model comparison plots official_plots/browser_harness_by_model_{light,dark}.png from benchmark-x-laminar@45b563b to replace the stale 2026-06-17 images. The plots now include new models (e.g., claude-opus-5, claude-fable-5, grok-4.5, kimi-k3, gpt-5.6-*, qwen3.8-max, deepseek-v4-flash-0731), remove dropped ones, and change open-weight bars to a gray fill with a blue dashed outline.

^{Written for commit 13bac02. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files

_{Re-trigger cubic}