[FR] Proper deterministic mode using -i + --deterministic

[spydmobile]

Summary

Implement proper deterministic fire modeling mode by passing both -i and --deterministic flags to FireSTARR. This produces a deterministic arrival-time raster (single prediction, no Monte Carlo), which when polygonalized produces a proper deterministic fire perimeter prediction — equivalent to Prometheus and WISE output.

Context

Replaces the old "pseudo deterministic" approach. With -i + --deterministic:

• FireSTARR runs a single deterministic scenario
• Output is an arrival-time raster (not probability)
• Polygonalizing the arrival-time raster produces a proper prediction perimeter

Related Issues

• Depends on: [FR] Add -i flag to all FireSTARR CLI invocations #150 (add -i flag to all calls)
• Related to: [BUG] Remove polygon perimeter params from Stage 3 UI #146 (remove polygon perim params)
• Related to: model mode selector (probabilistic/deterministic/long-term risk)

Acceptance Criteria

• When deterministic mode is selected, Nomad passes both -i and --deterministic to FireSTARR
• Arrival-time raster is produced and available
• Perimeter can be generated from the arrival-time raster
• Output is a single deterministic prediction, not a probability distribution

[spydmobile]

Blocked: --deterministic flag not yet implemented upstream in FireSTARR. Will implement once the upstream support lands.

[spydmobile]

in discussions with @jordan-evens : while the --deterministic is not operational, we can get the benefits by simply chaining the max_simulations in the ini file to 0 and then using only the fire arrival time grid to create a final perimeter.