The runner's hand-written JSON parser and writer, and its XML escaping,
are replaced by two established MIT libraries, vendored in third_party/:
yyjson 0.13.0 and pugixml 1.16. JsonValue and the JUnit model stay as they
are.

Both are compiled into Catch3's own translation units, so a project that
links its own yyjson or pugixml is not affected:
- src/Progmasoft/Runner/Yyjson.inl includes yyjson.c into Json.cpp with
  yyjson_api defined as static, so no yyjson symbol leaves that file.
- src/Progmasoft/PugiXml.inl includes pugixml header-only into
  XmlWriter.cpp with its namespace renamed to Progmasoft_Catch3_Pugi.
- Both are read as system headers, outside the warnings Catch3 builds
  with; they are .inl files, which the header install rules leave out.

JSON keeps its behaviour: strings are bytes and come back as written
(invalid UTF-8 is allowed both ways), non-finite numbers are written as
null, documents nested deeper than 256 levels are refused while they are
converted, and whole numbers are written as integers. Fractions are now
written as the shortest text that reads back as the same double.

JUnit XML stays equivalent; pugixml writes ' and > in attributes as they
are, U+FFFD as the character itself and empty elements as <x />. The
tests follow.

third_party/{yyjson,pugixml} each have BUILD.bazel, CMakeLists.txt,
meson.build, xmake.lua and premake5.lua, which only provide the include
directory to the library; CMake links them through BUILD_INTERFACE.

tools/scripts/updateThirdParty.py pins the version and sha256 of each
archive; --check, now a step of the header and license workflow, fails
when a vendored file differs from its archive, and --update writes them.
Renovate proposes new versions through a regex manager on that table.

The amalgamation now has a third file, catch_amalgamated_third_party.hpp,
with both wrappers and the libraries inlined; catch_amalgamated.cpp
includes it once. The documents and the release notes say so.

Catch2 compatibility means the API tests are written in: the macros, such
as TEST_CASE and REQUIRE, and the Catch:: namespace. It does not mean
Catch2's build names or header paths. find_package(Catch2) found Catch3,
and a project using both frameworks met two packages, two sets of targets,
two Catch.cmake modules and two catch2/ header trees with the same names.

Build names:
- CMake: project and package Catch3, targets Catch3::Catch3 and
  Catch3::Catch3WithMain, libraries Catch3 and Catch3Main, options
  CATCH3_*, lib/cmake/Catch3 with Catch3Config, and pkg-config catch3 and
  catch3-with-main. The version is Catch3's, 0.3.0, compatible within a
  minor version.
- The CMake scripts are Catch3.cmake (catch3_discover_tests),
  Catch3AddTests.cmake and Catch3ShardTests.cmake
  (catch3_add_sharded_tests); the helpers they define at ctest time have a
  catch3_ prefix. ParseAndAddCatchTests.cmake, deprecated upstream, is gone.
- Bazel //:catch3 and //:catch3_main, Meson catch3 and catch3-with-main
  (with override_dependency), Xmake catch3 and catch3_main, Premake Catch3
  and Catch3WithMain. Visual Studio projects get GUIDs of their own.
- The Progmasoft::Catch3 target and package are gone: property testing
  and snapshots are part of Catch3::Catch3. Their sources now build with
  the library's warning flags, so property failures are built field by
  field (no missing initializers) and the default property name is a
  thread-local pointer to the name its scope owns (no global destructor).

Headers: the engine moved from src/catch2 to src/Progmasoft/Catch3 with
Progmasoft names, so <catch2/catch_test_macros.hpp> is
<Progmasoft/Catch3/TestMacros.hpp>, <catch2/matchers/catch_matchers_string.hpp>
is <Progmasoft/Catch3/Matchers/String.hpp>, and interface headers are named
after their interface, such as Interfaces/IConfig.hpp. Include guards
became #pragma once. The installed headers go to include/Progmasoft.
src/Progmasoft/Context.cpp is StrategyContext.cpp, so no two sources share
a file name.

tools/scripts/upstreamFiles.txt lists the files that come from Catch2.
The license check expects BSL-1.0 on them and Progmasoft's header on the
rest of src/Progmasoft; the convenience-header check, the amalgamation
script and the surrogate tests take the engine's headers from it. The
amalgamated files are regenerated. The header-guard workflow checks for
#pragma once instead of checkguard.

Documents, the README and the release notes describe the new names.

Review Catch2 devel through 08092139210881f01a34e60c5f2fd6afa0ea4024,
the commit of 3.16.1, and apply the eleven changes since the last
reviewed revision in upstream order:

  d7683484  better message when a reporter cannot be initialized
  ea5020f0  custom argument validation in every first-party reporter
  aa01559e  throwing-reporter test also throws in assertionEnded
  45cd3987  noexcept on handleUnexpectedInflightException
  6adbd539  MSVC optimizations enabled again after the benchmark headers
  e87f2882  no quadratic scaling for NTTP test registration
  73d546cd  REQUIRE expands its arguments fewer times under GCC and Clang
  b710039a  decomposer operators as plain functions
  f899467b  type-erased streaming of reconstructed expressions
  8f0e70ca  retired macos-14 runner dropped
  08092139  version 3.16.1 and its release notes

All of them applied to the sources without a conflict. The amalgamated
distribution under extras/ conflicted because it is generated; it is
generated again from the sources of this repository, which also brings
it up to date with fork changes it had not picked up: the list-based
stream pool, the Clang diagnostic boundary and the cassert include.

No file under src/Progmasoft changes. The fork-owned texts that name
the engine version say 3.16.1, and docs/upstream-status.md records the
review. Upstream files keep their names, licenses and compiler options.

Built with Clang 22 on Windows and tested: 148 of 149 tests pass. The
one that fails, Reporters::CrashInJunitReporter, fails the same way on
devel without this change with that compiler.

Introduce deterministic property execution, built-in generators, shrinking, replayable seeds, and a separate Progmasoft-owned header API while preserving Catch2 compatibility targets and the C++14 engine baseline.

Add Bazel, Meson, Xmake, and Premake integration and tests alongside the existing CMake build. Replace Linux-only workflow coverage with Windows and macOS jobs and document the Catch2/Catch3 distinction.