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>

.github/labeler.yml

@@ -21,6 +21,17 @@ labels:
   files:
     - "cmake/.*"
 
+# other build systems
+- label: "CMake"
+  files:
+    - "(meson\\.build|meson_options\\.txt|BUILD\\.bazel|MODULE\\.bazel|Package\\.swift)"
+
+- label: "documentation"
+  files:
+    - ".github/ISSUE_TEMPLATE/.*"
+    - ".github/config\\.yml"
+    - ".github/(CONTRIBUTING|SECURITY|CODE_OF_CONDUCT|PULL_REQUEST_TEMPLATE)\\.md"
+
 - label: "CI"
   files:
     - ".github/workflows/.*"