- Add 21 new alternate techs across all 6 fields (computers, construction,
forcefields, planetology, propulsion, weapons), using icon frames 78-96
- Set research video paths for human and kestrelli species
- Expand tech sprite sheet from 8 to 10 rows to accommodate new frames
- Add fieldTechLevel() to VegaLogic: displays per-field level as highest
known tier × 5 plus extra known techs below the frontier
- Display field level in research screen headers
- Add verification tests for 3-way branching rungs, fieldTechLevel calculations,
and refine availability roll tests to measure unbranched rungs only
