Integrate Forward+ lighting with temporal rendering

include/faset/render/renderer.hpp

@@ -137,6 +137,7 @@ struct Snapshot {
     std::optional<CameraFrustum> camera_frustum{};
 };
 enum class VisibilityMode { Direct, GpuFrustum, GpuOcclusion };
+enum class LightingMode { Auto, Forward, Tiled };
 // CPU-only validation used before publishing a game or creating Vulkan pipelines.
 void validate_shader_bundle(const std::filesystem::path& directory);
 void validate_gpu_shader_bundle(const std::filesystem::path& directory);
@@ -149,6 +150,9 @@ struct RendererConfig {
     VisibilityMode visibility_mode{VisibilityMode::Direct};
     TemporalMode temporal_mode{TemporalMode::Off};
     float render_scale{1.f};
+    // Auto uses measured Forward on the reference workload. Tiled can be forced
+    // for comparison and falls back to Forward if its device path is unavailable.
+    LightingMode lighting_mode{LightingMode::Auto};
     // GPU counter readback is diagnostic-only; normal visibility uses no CPU feedback.
     bool visibility_diagnostics{false};
     // Optional isolated shader bundle, useful for editor preview and shader reload tests.
@@ -217,6 +221,11 @@ struct FrameStats {
     std::array<float, 2> temporal_jitter{};
     double gpu_temporal_resolve_ms{}, gpu_temporal_composite_ms{}, gpu_ui_ms{};
     std::vector<std::string> graph_passes;
+    double gpu_light_tiles_ms{};
+    std::uint32_t light_tile_count{};
+    // Optional tile-list readback, valid only when visibility diagnostics are on.
+    bool light_tile_counts_valid{};
+    std::uint32_t light_tile_candidate_count{}, light_tile_overflow_count{};
     std::string effective_lighting_path{"forward"};
     std::string device;
 };