libmpv 2026-08-14 + Vulkan loader

Same libmpv as libmpv-2026-08-14 (shinchiro 20260814, mpv v0.41.0-923-g7b8915bc1), with the Khronos Vulkan loader vulkan-1.dll bundled next to it.

Upstream's 2026-08-04 "vulkan: disable static loader" change gave libmpv-2.dll a load-time import of vulkan-1.dll, which only exists on systems whose GPU driver installed a Vulkan runtime. On machines with pre-Vulkan GPUs or the Microsoft Basic Display driver, LoadLibrary failed outright — black video, no sound (SubtitleEdit/subtitleedit#13856, upstream shinchiro/mpv-winbuild-cmake#831). The bundled loader fixes the import; with no Vulkan drivers present it simply enumerates zero ICDs and mpv's d3d11/OpenGL paths work as before.

vulkan-1.dll is from the LunarG Vulkan Runtime 1.4.357.0 (https://vulkan.lunarg.com/sdk/home#windows, Apache-2.0, Authenticode-signed; license text included in each zip).

• libmpv2-win64.zip — libmpv-2.dll byte-identical to mpv-dev-x86_64-20260814-git-7b8915bc1d.7z (non-v3, no AVX2 requirement), sha256 f709c7ca8b183bec76b8158bf0c45c53018c63366750729352612f228ff7bdea; x64 vulkan-1.dll sha256 cd862090370454630b31b174e3d4eb474fda38ea034998d1fe1767b0c99a8696
• libmpv2-win-arm64.zip — libmpv-2.dll byte-identical to mpv-dev-aarch64-20260814-git-7b8915bc1d.7z, sha256 1afe7d01a0f0b914b3042aba6373b88db5cee8820ea887a114fd3e6d29e1139e; ARM64 vulkan-1.dll sha256 cc5dd0bec8a7afef013c61ddd511d31500a3b3a45c229150a9ae73ead708ab76