[splincode]

Summary

• expand all 21 full answers in UX-метрики и проверка решений
• cover conversion, task success, time on task, drop-off, funnels and rage clicks with formulas and realistic examples
• explain tracking plans, event quality, privacy, frontend instrumentation and backend confirmation
• clarify A/B-test limitations, segmentation, qualitative/quantitative research, guardrails and causality
• connect frontend performance and Core Web Vitals to actual user tasks

Short answers remain unchanged. Every expanded answer adds practical mechanisms, trade-offs, edge cases and interview guidance.

Scope

• continues Расширить полные ответы во всех разделах #49, following merged docs: expand UI/UX microcopy answers #187
• changes only src/pages/ui-ux/index.md
• completes UX-метрики и проверка решений
• Когнитивные искажения в UI/UX and later subsections are out of scope

Verification

• Confirmed all 21 answers expanded, short answers preserved and only target subsection changed
• npm run format:check (CI)
• npm run build (CI)

Part of #49.