build, fix install target glob expansion for public headers

[steven-varga]

The install(FILES ${CMAKE_SOURCE_DIR}/include/decimal/* ...) line in CMakeLists.txt passes the literal * wildcard to CMake's install(FILES ...) command, which does not expand globs. This causes make install to fail with:

file INSTALL cannot find
"/home/steven/projects/libdecimal/include/decimal/*": No such file or directory.

Expected behavior: make install should copy all public headers into ${CMAKE_INSTALL_INCLUDEDIR}/decimal/.

Proposed fix: Replace the broken install(FILES ...) with install(DIRECTORY ...) so CMake installs the entire include/decimal directory tree.

Acceptance criteria:

• Configure and build in a fresh build directory.
• cmake --install build --prefix /tmp/libdecimal-install succeeds.
• /tmp/libdecimal-install/include/decimal/ contains bid.hpp, bcd.hpp, fixed.hpp, scaled.hpp, and utils.hpp.

[steven-varga]

Fixed in branch 37-build-fix-install-glob (commit efb608c).

Changes made:

• Replaced broken install(FILES ... include/decimal/* ...) with install(DIRECTORY ... include/decimal ...) so public headers install correctly.
• Fixed LIBBID header install scope by setting libbid_static_include_dir as a CACHE variable (PARENT_SCOPE only propagated to the intermediate thirdparty/ directory, leaving it empty in the top level, which caused the install to walk the filesystem root).
• Removed redundant install(FILES ${libbid_static_archive} ...) because install(TARGETS libbid_static EXPORT ...) already installs the archive.
• Renamed CMake package config files from libdecimal_config.cmake / libdecimal_config_version.cmake to libdecimal-config.cmake / libdecimal-config-version.cmake so find_package(libdecimal REQUIRED) can discover them.

Verified:

• Clean configure + build + test (11/11 tests pass).
• cmake --install build --prefix /tmp/libdecimal-install succeeds without errors and installs only the expected files.
• A downstream consumer project using find_package(libdecimal REQUIRED) and target_link_libraries(... libdecimal::libdecimal) builds and runs correctly.

[steven-varga]

Additional fix pushed to 37-build-fix-install-glob (commit 89cfffd): set the LIBBID static library OUTPUT_NAME to bid_static. Previously CMake auto-prefixed lib to the target name libbid_static, producing liblibbid_static.a. Now the installed artifact is libbid_static.a. Verified via clean build, install, and downstream consumer test.