Add tag-triggered release workflow with portable binary packaging

[particlesector]

Summary

• Adds .github/workflows/release.yml: pushing a version tag (v[0-9]+.[0-9]+.[0-9]+*) builds Windows (MSVC 2026) and Linux (GCC) binaries using the same build recipe as ci.yml, runs the test suite, cmake --installs each into a relocatable bin/ + share/chiselcad/{shaders,resources} layout, packages each as a zip/tarball, and publishes both to a GitHub Release named after the tag.
• Fixes a bug that would have made those release binaries unusable: CHISELCAD_SHADER_DIR/CHISELCAD_RESOURCE_DIR were baked in at compile time as absolute paths into the CI checkout tree, so a binary zipped up from CI and run on any other machine would fail to find its shaders/fonts.
  • Adds src/util/ResourcePaths.{h,cpp} with Win32/Posix executable-path backends, which resolve shader/resource directories relative to the running executable (preferring the installed share/chiselcad/ layout) and fall back to the old compile-time paths for in-place dev builds.
  • Application.cpp / CsgEvaluator.cpp now go through this resolver instead of the raw CHISELCAD_SHADER_DIR/CHISELCAD_RESOURCE_DIR macros.
  • Pipeline.cpp's shader path building switched from string concatenation (which relied on a trailing-slash convention) to std::filesystem::path joins.
  • CMakeLists.txt wires the new sources into both the chiselcad and chiselcad_tests targets.
  • Windows packaging also copies the DLLs vcpkg's dynamic triplet drops next to the built exe (cmake --install doesn't do this automatically); Linux's static triplet needs no extra step.

Test plan

• CI (ci.yml) passes on this branch (Windows + Linux build/test)
• Push a vX.Y.Z tag against this branch (or after merge) and confirm release.yml produces a Windows zip and a Linux tarball and attaches both to a GitHub Release
• Unzip/untar each archive on a clean machine and confirm the app launches and finds its shaders/fonts (i.e. bin/chiselcad(.exe) next to share/chiselcad/{shaders,resources} resolves correctly)

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Generated by Claude Code

[particlesector]

Reviewed. This is solid — I traced the actual bug carefully:

• install(DIRECTORY ${SHADER_BINARY_DIR} DESTINATION share/chiselcad) (no trailing slash) installs to share/chiselcad/shaders/*.spv, and install(DIRECTORY resources/ DESTINATION share/chiselcad/resources) (trailing slash) installs contents directly to share/chiselcad/resources/*. Both match installedCandidate()'s exeDir/../share/chiselcad/{shaders,resources} exactly — the runtime resolver lines up with the existing install rules.
• The Pipeline.cpp switch from string concat to std::filesystem::path joins correctly fixes the trailing-slash assumption.
• release.yml's Windows/Linux job config (runner labels, Vulkan SDK version, vcpkg commit) matches ci.yml exactly, as claimed.
• ResourcePathsPosix.cpp's __linux__-only guard mirrors the existing FileWatcherInotify.cpp convention (UNIX == Linux in this project), so it's not a new gap.

One minor, non-blocking observation: in resolveShaderDir()/resolveResourceDir(), if a stale share/chiselcad/ directory ever ends up next to a dev build (e.g. from an errant local cmake --install), it'll silently win over the live build-tree shaders since exists() is the only check. Unlikely in practice given the CI install prefix is install/, not worth changing.

Approving.

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Generated by Claude Code