texture_cache: dedupe region queries with a picked flag

src/graphics/host_gpu/renderer/image/image.h

@@ -149,7 +149,7 @@ public:
 	ImageUsage       usage;
 	ImageBinding     binding;
 	bool             registered     = false;
-	mutable uint32_t query_epoch    = 0;
+	mutable bool     picked         = false; // Set only while FindImagesInRegion collects it.
 	uint64_t         track_addr     = 0;
 	uint64_t         track_addr_end = 0;
 	ImageId          depth_id {};