feat: Windows portability - path separators, LF line endings, UTF-8 decoding and output, msvcrt lock fallback (#152)

Files changed:
- .gitattributes
- CHANGES.md
- VERSION
- raw/CONTRACT.md
- tools/README.md
- tools/chemenu/commands/_util.py
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/commands/doctor.py
- tools/chemenu/commands/eval_cmd.py
- tools/chemenu/commands/git_publish.py
- tools/chemenu/commands/index_build.py
- tools/chemenu/commands/lint.py
- tools/chemenu/commands/log_append.py
- tools/chemenu/commands/migrate_cmd.py
- tools/chemenu/commands/provenance_cmd.py
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/commands/run_budget.py
- tools/chemenu/commands/upstream_cmd.py
- tools/chemenu/commands/version_cmd.py
- tools/chemenu/commands/work_cmd.py
- tools/chemenu/config.py
- tools/chemenu/corpus_cache.py
- tools/chemenu/filelock.py
- tools/chemenu/frontmatter_io.py
- tools/chemenu/kb_scan.py
- tools/chemenu/kb_state.py
- tools/chemenu/lint_core.py
- tools/chemenu/prerequisites.py
- tools/chemenu/provenance.py
- tools/chemenu/search/base.py
- tools/chemenu/search/ripgrep.py
- tools/chemenu/telemetry/writer.py
- tools/chemenu/tests/test_dist_cmd.py
- tools/chemenu/tests/test_portability.py
- tools/chemenu/tests/test_search.py
- tools/chemenu/tests/test_trace_ingest.py
- tools/chemenu/type_resolver.py
- tools/chemenu/upload.py
- tools/chemenu/version.py
- tools/run_wikitool.py
- tools/trace_ingest.py

tools/chemenu/provenance.py

@@ -349,7 +349,7 @@ def page_raw_files(pages: dict[str, Page], page: Page) -> list[str]:
 def uncovered_raw_files(raw_dir: Path, pages: dict[str, Page]) -> list[str]:
     """Raw files with no source page claiming to cover them."""
     covered = set(source_pages_by_raw_file(pages))
-    all_raw = {str(p.relative_to(config.ROOT)) for p in config.iter_raw_files(raw_dir)}
+    all_raw = {p.relative_to(config.ROOT).as_posix() for p in config.iter_raw_files(raw_dir)}
     return sorted(all_raw - covered)