Move the tools from Python to C++17 and Bazel

The scripts in use become programs run with `bazelisk run //tools:<tool>`,
and arguments follow `--`:

  amalgamate     the single-file distribution; --check only compares it
  check          licenses, convenience headers, header guards, file names,
                 versions and whether the distribution is up to date
  third-party    compares third_party/ with its archives, or writes it
  version        prints the version, or moves every place that states it
  release-notes  prints a section of the release notes
  repo-info      reports the checkout and the tools on PATH; --json writes
                 it through yyjson, with the fields of Tala's repo-info

amalgamate writes what the Python script wrote, byte for byte, except for
the time of generation. That line is gone so that the output is
deterministic and --check can compare it.

MODULE.bazel now pins the archives of third_party/ by version and sha256,
so Bazel fetches and checks them instead of a tool of ours, and Renovate
reads the versions there.

Scripts nobody used are gone: fixWhitespace, updateDocumentSnippets,
buildAndTest, and updateDocumentToC, which rewrote unrelated documents.
CheckConvenienceHeaders leaves CTest, since //tools:check runs it in CI.
The Python of tests/TestScripts stays: those are tests, not tools.

1 files changed, 69 insertions, 0 deletions

diff --git a/tools/VersionMain.cpp b/tools/VersionMain.cpp
new file mode 100644
index 00000000..a7fb123a
--- /dev/null
+++ b/tools/VersionMain.cpp
@@ -0,0 +1,69 @@
+// Copyright (c) 2026 Progmasoft.
+// SPDX-License-Identifier: MPL-2.0 WITH AdditionRef-Progmasoft-Exception-2.0
+
+// bazelisk run //tools:version                  prints the current version
+// bazelisk run //tools:version -- --next        moves to the next version
+// bazelisk run //tools:version -- 0.3.1.0       moves to that version
+//
+// Moving writes every place that states the version, and the amalgamation.
+
+#include <iostream>
+#include <string>
+#include <string_view>
+
+#include "tools/Amalgamation.hpp"
+#include "tools/Repository.hpp"
+#include "tools/Versions.hpp"
+
+int
+main(int argc, char **argv)
+{
+    using namespace Progmasoft::Catch3::Tools;
+
+    if (argc > 2)
+    {
+        std::cerr
+            << "usage: bazelisk run //tools:version [-- --next|<version>]\n";
+        return 2;
+    }
+    const auto root = RepositoryRoot();
+    if (!root)
+    {
+        std::cerr << "run this tool with bazelisk run\n";
+        return 2;
+    }
+    Problems problems;
+    const auto current = CurrentVersion(*root, problems);
+    if (!current)
+    {
+        return Finish(problems);
+    }
+    if (argc == 1)
+    {
+        std::cout << *current << '\n';
+        return 0;
+    }
+    const std::string_view argument{ argv[1] };
+    const auto parsed = ParseVersion(
+        argument == "--next" ? *current : std::string{ argument });
+    if (!parsed)
+    {
+        std::cerr << "not a version of three or four numbers: " << argument
+                  << '\n';
+        return 2;
+    }
+    const auto version
+        = FormatVersion(argument == "--next" ? NextVersion(*parsed) : *parsed);
+    SetVersion(*root, version, problems);
+    if (problems.empty())
+    {
+        WriteAmalgamation(*root,
+                          GenerateAmalgamation(*root, problems),
+                          problems);
+    }
+    if (problems.empty())
+    {
+        std::cout << *current << " -> " << version << '\n';
+    }
+    return Finish(problems);
+}