FEAT: outcome breakdown visualization on the scenario run page

[WatchTree-19]

Description

Adds an accessible outcome-breakdown bar to the scenario run page, showing the distribution of attack outcomes (success, failure, undetermined, error) across a run's executions with per-outcome counts and percentages. The intent is that you can see at a glance how a run went, rather than reading the atomic-group table row by row. It sits between "Overall progress" and "Atomic attack groups", and it is computed from results the page already loads, so no backend change is required.

This addresses the "visualizing results from attacks in the GUI" area that Roman Lutz (@romanlutz) and I discussed alongside the scorer work in #2626 and #2628.

The change adds a pure utility, summarizeAttackOutcomes, which returns counts, total and percentages and is defensive about missing or unrecognised outcomes; a new OutcomeSummaryBar Fluent UI v9 component with co-located styles, fill colours aligned to OutcomeBadge semantics, and a role="img" element whose aria-label reads the full breakdown for screen readers; and the wiring into ScenarioRunPage.

Tests and Documentation

attackOutcomeSummary.test.ts covers counts, percentages, empty input and malformed-outcome handling. OutcomeSummaryBar.test.tsx covers segment rendering, the accessible summary label, legend counts and percentages, and the empty-state hint. The existing ScenarioRunPage.test.tsx heading assertion is updated for the new section. tsc --noEmit is clean, eslint --max-warnings 0 is clean, and jest passes across the util, component and run-page suites (28 tests). No JupyText changes, since this is frontend-only.

The change follows the frontend style guide: tokens-only styling in a co-located .styles.ts, inline style used only for the genuinely dynamic segment width, data-testid selectors, and accessible markup.

[Roman Lutz (romanlutz)]

Can you add screenshots to the PR description? Also #2378 sounds like it may have overlap.

[WatchTree-19]

Roman Lutz (@romanlutz) screenshots coming, though flagging one thing first since it may change what is worth screenshotting.

You are right about #2378 overlapping. I pulled the diff. It is not the same feature, but it lands in the same place:

#2378 adds per-attack outcome badges to ScenarioRunPage.tsx (formatOutcome, outcomeColor, the Badge in the attack summary) plus a per-group succeeded / errors tally. This PR adds a run-wide distribution bar with counts and percentages across all executions. Different question being answered, one reads "what happened to this attack", the other "how did this run go overall".

Where they actually collide is mechanical. #2378 touches ScenarioRunPage.tsx at +149/-5 and ScenarioRunPage.styles.ts at +77, and this PR edits both. It also brings its own outcomeColor mapping, which would sit alongside the fill colours here, so we would end up with two colour maps for the same four outcomes.

#2378 is layer 7 of a stack with layers already merged, and mine is a single file addition, so mine should give way rather than the other way round. Happy to rebase this on top once #2378 lands and fold the colour mapping into whatever it establishes, so there is one source of truth for outcome colour.

One question that decides how I rebase: would you rather the distribution bar stayed a separate component slotted into the page, or became part of the result-details structure #2378 introduces? I will take direction either way.