Type projected city object results

[esnya]

Summary

• make surface projection info represent only projected surfaces with concrete height ranges
• skip empty surfaces at projection-info creation before facade UV, bottom cull, and generated LOD1 roof selection logic
• remove nullable height checks and null-forgiving height access from both projection policy paths

Verification

• dotnet test tests\PlateauResoniteLink.Tests\PlateauResoniteLink.Tests.csproj --configuration Release --no-restore --filter "FullyQualifiedName~CityGmlSurfaceProjectionPolicyTests|FullyQualifiedName~GeneratedLod1RoofCityObjectFactoryTests" --verbosity normal -m:1 --disable-build-servers -p:UseSharedCompilation=false (36 passed)
• git diff --check
• dotnet restore PlateauResoniteLink.sln --locked-mode --disable-build-servers
• dotnet format whitespace . --folder --verify-no-changes
• dotnet build PlateauResoniteLink.sln --configuration Release --no-restore --disable-build-servers -m:1 -p:UseSharedCompilation=false
• dotnet test PlateauResoniteLink.sln --configuration Release --no-restore --verbosity normal -m:1 --disable-build-servers -p:UseSharedCompilation=false (1015 passed)
• Fake Live Sink canonical dump for plateau-13213-higashimurayama-shi-2020, mesh 53395325, packages dem,bldg, terrain mesh grid matched the baseline with git diff --no-index; temp dump removed

[esnya]

restack で dynamic terrain projection の runtime geometry cast 除去をこの PR に移しました。surface height range と合わせて、projection 結果を型で持つ境界として review できる単位にしています。\n\n最上位 #356 の tree は restack 前と同一です。検証: restore / format whitespace verify / Release build / Release test (1038 passed)。