Add defensible live legal temperature alerts

[jonashertner]

Outcome

• add an in-page legal screen for fresh BAFU river-temperature readings strictly above 25.0 °C
• distinguish a review trigger from a legal finding and disclose the missing attribution, mixing, permit, and exception evidence
• link the exact Fedlex basis and LINDAS live source
• provide accessible station drill-down and responsive five-language copy
• add executable freshness, missing-value, and strict-threshold contracts

Verification

• npm run release
• npm run check:links
• Chrome: 1440×900, 390×844, 320×568