@mytec: feat: Phase 3.0 Architecture Refactor ✅

Major refactoring of RFCP backend:
- Modular propagation models (8 models)
- SharedMemoryManager for terrain data
- ProcessPoolExecutor parallel processing
- WebSocket progress streaming
- Building filtering pipeline (351k → 15k)
- 82 unit tests

Performance: Standard preset 38s → 5s (7.6x speedup)

Known issue: Detailed preset timeout (fix in 3.1.0)

backend/app/api/routes/coverage.py

@@ -11,6 +11,7 @@ from app.services.coverage_service import (
     CoveragePoint,
     apply_preset,
     PRESETS,
+    select_propagation_model,
 )
 from app.services.parallel_coverage_service import CancellationToken
 
@@ -58,6 +59,12 @@ async def calculate_coverage(request: CoverageRequest) -> CoverageResponse:
     effective_settings = apply_preset(request.settings.model_copy())
     models_used = _get_active_models(effective_settings)
 
+    # Add the selected propagation model for the first site's frequency
+    env = getattr(effective_settings, 'environment', 'urban')
+    primary_model = select_propagation_model(request.sites[0].frequency, env)
+    if primary_model.name not in models_used:
+        models_used.insert(0, primary_model.name)
+
     # Time the calculation
     start_time = time.time()
     cancel_token = CancellationToken()
@@ -182,7 +189,7 @@ async def get_buildings(
 
 def _get_active_models(settings: CoverageSettings) -> List[str]:
     """Determine which propagation models are active"""
-    models = ["okumura_hata"]  # Always active as base model
+    models = []  # Base propagation model added by caller via select_propagation_model()
 
     if settings.use_terrain:
         models.append("terrain_los")