style(dashboard): sharpen dark results command center

[christso]

Summary

• sharpens Dashboard dark-mode run/result surfaces with higher-contrast panels, table shells, and metric strips
• gives failing rows, aggregate grading, and nested child assertions clearer red severity treatment
• de-emphasizes duplicate score labels in nested grading by keeping compact bars unlabeled when the score is already shown nearby
• fixes mobile eval-detail header/tab overflow so the 390px child-assertion view no longer shows a horizontal scrollbar

Validation

• bun --filter @agentv/core build
• bun --filter @agentv/sdk build
• bun --filter @agentv/dashboard build (passes with existing Vite large chunk warning)
• bun --filter @agentv/dashboard test (162 pass, 0 fail)
• agent-browser desktop/mobile UAT on local synthetic dashboard-child-assertions run
• agent-browser errors on desktop and mobile: no output
• mobile overflow diagnostic after final fix: scrollWidth: 390, clientWidth: 390 at a 390px viewport

Evidence

Private evidence branch: agentv-private:evidence/av-3yal-dashboard-command-center-polish
Private evidence commit: 38f03a7b55211648613d971d5fc8d864dcb494d4

Captured updated desktop/mobile run overview, split row detail, full failing grading page, and nested mobile child assertions. The branch README includes the private issue 15 references, av-cs91 regression screenshot, pre-change local baseline captures, and the final no-overflow mobile recapture.

Bead: av-3yal

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