Uno 2.7.3

• Updated the bundled Uno C++ solver to upstream release 2.7.3. The R-packaging patch set was rebased onto v2.7.3; the C API is backward-compatible (the binding is unchanged). One internal fix: Uno 2.7.3 relocated Options::dump_default_options(), so its console output is re-routed through the R-output mechanism (UNO_COUT) to keep the compiled library free of raw std::cout for the CRAN compiled-code check.

• Added inst/COPYRIGHTS documenting the copyright holders and licenses of the bundled third-party libraries: the Uno C++ solver and HiGHS, including the components HiGHS itself bundles (AMD, METIS, pdqsort, zstr, rcm, filereaderlp, Catch2, and CLI11). All are permissive and MIT-compatible (MIT / BSD-3-Clause / Apache-2.0 / zlib / Boost Software License 1.0); none is copyleft. A Copyright: file inst/COPYRIGHTS field and a cph entry for the HiGHS development team record this in the package metadata. Because the file lives under inst/, the attribution survives installation. MUMPS (reached at run time through the GPL-licensed rmumps package) and BQPD are not bundled.