Task 238: Margin Gauge Visualization Component

Status: DONE

Description

Add a margin gauge visualization component — horizontal bar charts that show how close each critical parameter was to its limit. DESIGN.md specifically calls for "ゲージ/バーチャート: 各パラメータが限界値にどこまで近づいたかを一目で示す".

Scope

1. Component: margin-gauge MDX code fence type

• New MDX code fence type margin-gauge parsed in mdx-parser.ts / episode-mdx-parser.ts
• Rendered as horizontal bars showing actual vs limit
• Color coding: green (safe, >20%), yellow (tight, 5-20%), red (critical, <5%)
• Shows percentage and absolute values

2. Data: Add margin gauges to cross-episode.md

Key margins to visualize:

• Nozzle life: 55h38m available vs 55h12m used → 26 min margin (0.78%)
• Radiation dose: ~560 mSv total vs 600 mSv NASA limit → 40 mSv margin (6.7%)
• Mass boundary EP01: actual vs 299t limit
• Mass boundary EP03: actual vs 452.5t limit
• Shield life EP04: 14 min available vs 8 min needed → 6 min margin (43%)
• Chain probability: 46% overall success

3. Tests

• TDD: Unit tests for gauge rendering
• Article content tests for gauge data accuracy
• E2E test for gauge rendering on page