add video frame type and debug viewer and debug test source

the test source thread will always exist for now
the debug view will open a window for each connection

src/frame_streams/sdl/video.hpp

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <SDL3/SDL.h>
+
+#include <cstdint>
+#include <memory>
+
+// https://youtu.be/71Iw4Q74OaE
+
+inline void nopSurfaceDestructor(SDL_Surface*) {}
+
+// this is very sdl specific
+// but allows us to autoconvert between formats (to a degree)
+struct SDLVideoFrame {
+	// micro seconds (nano is way too much)
+	uint64_t timestampUS {0};
+
+	std::unique_ptr<SDL_Surface, decltype(&SDL_DestroySurface)> surface {nullptr, &SDL_DestroySurface};
+
+	// special non-owning constructor
+	SDLVideoFrame(
+		uint64_t ts,
+		SDL_Surface* surf
+	) {
+		timestampUS = ts;
+		surface = {surf, &nopSurfaceDestructor};
+	}
+	SDLVideoFrame(SDLVideoFrame&& other) = default;
+	// copy
+	SDLVideoFrame(const SDLVideoFrame& other) {
+		timestampUS = other.timestampUS;
+		if (static_cast<bool>(other.surface)) {
+			surface = {
+				SDL_DuplicateSurface(other.surface.get()),
+				&SDL_DestroySurface
+			};
+		}
+	}
+	SDLVideoFrame& operator=(const SDLVideoFrame& other) = delete;
+};
+