Agentic assessment question bank and visual system

What changed

• The agentic assessment bank grew toward 50 UI work-sample questions across spec-driven, debug, and brownfield formats.
• Candidate review, evidence tabs, reports, builders, and notification accents moved onto the warm AlgoArena theme tokens.
• Team member management, model pricing checks, testimonial rails, and screenshot-capable model picking were cleaned up around the assessment story.