Switch test map to use generated terrain (mapfile="")

- Remove .smf file from test_fixtures/minimal_test_map.sdd/
- Set mapfile="" in mapinfo.lua to use Spring's map generation
- Matches SpringBoard's config.json approach with map generation options

Status: Still debugging segfault after "Loading Feature Definitions"
- Using spring-headless --isolation
- MAPOPTIONS: new_map_x=10, new_map_y=8
- MODOPTIONS: MapSeed=42
- Map scans successfully but crashes during load

Need to identify what's missing for generated map support.

Author: claude

test_fixtures/minimal_test_map.sdd/mapinfo.lua

@@ -5,7 +5,7 @@ local mapinfo = {
   description = "Minimal 2x2 test map for CI smoke tests",
   author      = "Auto-generated",
   version     = "v1.0",
-  mapfile     = "maps/TestMinimal2x2.smf",
+  mapfile     = "",
   modtype     = 3,
   depend      = {"Map Helper v1"},
   replace     = {},