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/README.md

@@ -51,6 +51,15 @@ the recorded path - or, with no file at all (the test suite, a bare
 but names a path that has gone raises `ToolPathError`, which the CLI turns
 into an `ERROR` line pointing at the preflight rather than a traceback.
 
+The package runs natively on Windows as well, which CI never does. So the rules that keep
+it portable are held by reading the source, in `tests/test_portability.py`: a path that
+becomes a string goes through `.as_posix()`, a text file is opened with `encoding=` and
+written with `newline="\n"`, a `subprocess` call with `text=True` names `encoding="utf-8"`,
+and only `filelock.py` imports `fcntl` or `msvcrt`. An `rg` path comes back with `\` on
+Windows even with `--path-separator /`, so `search/ripgrep.py` converts it where it parses
+the JSON. `.gitattributes` keeps every text file LF in a checkout, `raw/` and `incoming/`
+excepted.
+
 `jsonschema` and `PyYAML` are hard dependencies, not optional extras: schema
 validation is the tool's whole safety net, so `cli.py` fails loudly with the
 fix rather than degrading silently.
@@ -61,7 +70,7 @@ fix rather than degrading silently.
 tools/
   wikitool                 entry point (POSIX sh): stops with exit 42 until the preflight has passed
   wikitool.ps1             the same entry point for PowerShell 7, which resolves `tools/wikitool` to this file first
-  run_wikitool.py          what the launcher runs with the venv's Python - puts chemenu on sys.path without PYTHONPATH
+  run_wikitool.py          what the launcher runs with the venv's Python - puts chemenu on sys.path without PYTHONPATH, sets stdout/stderr to UTF-8
   preflight.sh             checks prerequisites.txt, records .wikitool-tools.json, creates .venv (POSIX sh); as the release asset, downloads and unpacks the stack first
   preflight.ps1            the same for PowerShell 7; also checks the execution policy and the Mark of the Web
   prerequisites.txt        what the machine needs, one `|`-separated line per tool - read by the preflight and `doctor`
@@ -74,6 +83,7 @@ tools/
     api.py                 the in-process entry point - point Chemenu at a corpus and read it
     errors.py              ChemenuError / ValidationError / BackendError
     toolpaths.py           where git and rg are started from: .wikitool-tools.json, bare name only without the file
+    filelock.py            an exclusive lock on an open file, flock on POSIX and msvcrt on Windows - the only module that imports either
     prerequisites.py       prerequisites.txt read from Python, plus the platform and long-path questions `doctor` asks
     corpus_cache.py        one parsed corpus per commit, never cached while the tree is dirty
     kb_scan.py             page iteration/loading over kb/