perf(vulkan): increase shader threads for high-end Android devices

- 6+ core devices: Use n-2 threads (e.g., 8-core uses 6 threads)
- Lower-end devices: Keep 3 free cores as before
- Improves shader compilation speed during game loading

Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/video_core/renderer_vulkan/vk_pipeline_cache.cpp

@@ -268,8 +268,11 @@ size_t GetTotalPipelineWorkers() {
     const size_t max_core_threads =
         std::max<size_t>(static_cast<size_t>(std::thread::hardware_concurrency()), 2ULL);
 #ifdef ANDROID
-    // Leave at least a few cores free in android
-    constexpr size_t free_cores = 3ULL;
+    // PROJECT THOR OPTIMIZATION: Shader Threading for high-end Android devices
+    // For 8-core devices like SD8 Gen 2 (AYN Thor): Use 6 threads (8 - 2 = 6)
+    // For 6-core devices: Use 4 threads (6 - 2 = 4)
+    // For lower-end devices: Leave 3 cores free as before
+    const size_t free_cores = (max_core_threads >= 6ULL) ? 2ULL : 3ULL;
     if (max_core_threads <= free_cores) {
         return 1ULL;
     }