ci: install libboost-filesystem-dev in shared C++ setup action

Co-authored-by: makr-code <150588092+makr-code@users.noreply.github.com>

Author: Copilot

.github/actions/setup-cpp-build/action.yml

@@ -66,7 +66,7 @@ runs:
         # Base packages required by every C++ CI job. Vulkan/GLSL tooling is
         # required for ThemisDB's GPU backend checks in Linux CI and local
         # validation runs that configure the Vulkan-capable build presets.
-        BASE_PKGS="cmake ninja-build ${{ inputs.cc }} ${{ inputs.cxx }} libgtest-dev pkg-config git libfmt-dev libboost-dev libvulkan-dev glslc"
+        BASE_PKGS="cmake ninja-build ${{ inputs.cc }} ${{ inputs.cxx }} libgtest-dev pkg-config git libfmt-dev libboost-dev libboost-filesystem-dev libvulkan-dev glslc"
         # Append optional extra packages (guard against empty string)
         EXTRA="${{ inputs.extra-packages }}"
         # shellcheck disable=SC2086