Add vehicle speed estimation with moving map markers

[bmander]

Summary

• Adds a speed estimation engine using gamma distributions fitted to real-time AVL data, with schedule-based fallback
• Implements moving map markers that interpolate vehicle positions between AVL updates using estimated speeds along routes
• Adds PDF (probability density function) overlay rendering on the map to visualize position uncertainty
• Includes debug views (trajectory graphs, vehicle data inspector, route debug) for development and tuning
• Extends OBA API model classes with trip schedule and speed-related fields

Test plan

• Unit tests included for gamma distribution math, speed model, and trip schedule parsing
• Instrumented test for end-to-end speed estimator behavior
• Manual verification: observe vehicles moving smoothly between updates on the map
• Verify debug views accessible and displaying correct data