Clean up non-code files (#5801)

* Clean up README, contribution guide, and repository metadata

- REUSE.toml: fix the Hedley path and SPDX id (CC0-1.0), mark the docset
  icons as the public-domain JSON logo
- CITATION.cff: v3.12.0 was released on 2025-04-11
- FILES.md: list all workflows, describe the Meson option defaults
- README: ctest -LE, table of contents, typos, stale Android/MinGW advice,
  moved links, merge duplicate Thanks entries, list the analysis tools
  used in CI
- CONTRIBUTING: iterative parser, json_literals.hpp is generated, links
- .gitignore: backups and release outputs; .gitattributes: mark
  generated files
- labeler: label other build systems and .github documentation
- MODULE.bazel: add the module version

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Clean up CI, CMake, Makefile, and Bazel files

- CMakeLists.txt: avoid VERSION_GREATER_EQUAL, which CMake < 3.7 lacks
- ci.cmake: test JSON_DisableTupleReferenceConversion in ci_cmake_flags,
  remove unused variables and unreachable per-compiler targets, look up
  Clang tools consistently, forward CMAKE_CXX_FLAGS to ci_module_cpp20,
  format json_literals.hpp and remove backups in ci_test_amalgamation
- BUILD.bazel: add json_literals.hpp to the single-header target
- workflows: format json_literals.hpp before copying it, drop the obsolete
  natvis --version plumbing, name natvis and macro_builder in failure
  messages, drop the duplicate amalgamation job, install Valgrind only
  where needed, republish docs on version bumps, fix stale names
- Makefile: complete .PHONY and help, check-amalgamation always restores
  the checked-in files, natvis uses its own venv, macro_builder_check
  installs astyle, clean removes the fuzzer binaries
- remove tools/amalgamate/config_json_view.json (json_view.hpp is not on
  develop yet)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix inaccuracies in the documentation

- version history: json_base_class_t (3.11.3), JSON_HAS_CPP_11 (3.10.0),
  JSON_HAS_RANGES exclusions, define-type macros, ABI tags
- releases: 3.12.0 raised the minimum CMake version
- from_*: the (ptr, len) overloads are deleted, not removed, in 4.0.0
- contains/count/find: document the deleted integral overloads
- add JSON_HAS_RANGE_VIEW_CONVERSION and list the JSON_HAS_* macros in
  the macro overview
- mention BON8 and error_handler where binary formats are listed
- broken links, outdated URLs, warning count, Hunter v0.26.12
- copy_markdown_source hook: expand snippets in the Markdown copies

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Pass /EHsc to the Windows C++20 module build

ci_module_cpp20 now forwards CMAKE_CXX_FLAGS to the module build. The
Windows workflow sets CMAKE_CXX_FLAGS, which replaces CMake's MSVC
defaults including /EHsc, so <chrono> failed with C4530 under /WX.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

docs/mkdocs/hooks/copy_markdown_source.py

@@ -2,12 +2,30 @@
 
 # Creates a `<path>.md` sibling of each HTML output (for example,
 # `features/comments/` becomes `features/comments.md`) so agents and tools can
-# fetch the raw Markdown directly instead of parsing rendered HTML.
+# fetch the raw Markdown directly instead of parsing rendered HTML. The
+# `--8<-- "path"` lines of pymdownx.snippets are expanded with the extension's
+# own preprocessor and the settings from mkdocs.yml, so the copies contain the
+# included example code and files instead of the include directives.
 
+import io
 import os
-import shutil
+
+import markdown
+from pymdownx.snippets import SnippetMissingError
 
 _pages = []
+_snippets = None
+
+
+def on_config(config):
+    global _snippets
+    md = markdown.Markdown(
+        extensions=["pymdownx.snippets"],
+        extension_configs={"pymdownx.snippets": config["mdx_configs"].get("pymdownx.snippets", {})},
+    )
+    _snippets = md.preprocessors["snippet"]
+    _snippets.auto_append = []  # the glossary is only needed to render abbreviations
+    return config
 
 
 def on_files(files, config):
@@ -22,4 +40,11 @@ def on_post_build(config):
         url = file.url.rstrip("/")
         target = os.path.join(site_dir, (url or "index") + ".md")
         os.makedirs(os.path.dirname(target), exist_ok=True)
-        shutil.copyfile(file.abs_src_path, target)
+        with io.open(file.abs_src_path, encoding="utf-8", newline="") as source:
+            text = source.read()
+        try:
+            text = "\n".join(_snippets.run(text.split("\n")))
+        except (SnippetMissingError, OSError):
+            pass  # keep the include directives; the regular build reports the missing file
+        with io.open(target, "w", encoding="utf-8", newline="") as copy:
+            copy.write(text)