[Lacikika]

Adds Migration 067: Highway Road Degradation, Heavy Freight Transit Wear, & Infrastructure Repair Contracts. Implements pure deterministic math for pavement stress (4th-power law), road quality decay, dynamic vehicle traction handling penalties, and asphalt/resurfacing repair contracts across nyx_vehicles, nyx_services, nyx_treasury, and nyx_ui. Includes complete Python and in-engine Lua test suites.

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PR created automatically by Jules for task 3631026750385723113 started by @Lacikika

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