feat: raw capture / raw status / --replaces-bundle - documentation from git repositories as a bundle, with drift reporting (#177)

New repo_capture module: resolve a branch or tag-pattern ref rule, fetch it
shallowly by name into a bare cache, read the glob-selected files as blobs,
and record repo/ref/commit/globs/capture fields in _capture.json. raw status
reports changed captured bundles as A/M/D; raw accept --replaces-bundle swaps
a captured bundle for its new edition at the same address. iter_raw_files now
skips _capture.json and anchors the CONTRACT.md exclusion to raw/CONTRACT.md.

Files changed:
- .gitignore
- CHANGES.md
- README.md
- VERSION
- instructions/wiki-ingest/SKILL.md
- raw/CONTRACT.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/cli_contract.py
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/config.py
- tools/chemenu/repo_capture.py
- tools/chemenu/tests/test_cli.py
- tools/chemenu/tests/test_raw_capture.py

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

README.md

@@ -217,6 +217,14 @@ text derived from it with a header recording where and when it was fetched. Behi
 login, save the page from your browser into `incoming/` (HTML only) instead; the LLM derives the
 same text from that file with `raw fetch --html`. See [raw/CONTRACT.md](raw/CONTRACT.md).
 
+Documentation that lives in a git repository is captured, not copied: `tools/wikitool raw capture
+<repo-url> --ref main --path 'docs/**/*.md' --name <bundle> ...` writes the matching files, byte
+for byte, into `incoming/<bundle>/` together with a `_capture.json` manifest naming the repository,
+the ref rule and the commit. Later, `tools/wikitool raw status` tells you which captured bundles
+have fallen behind their repository, file by file; `raw capture --update` and `raw accept
+--replaces-bundle` take the new edition in as a whole. Git uses your own keys and credential
+helpers - nothing is stored in the repository.
+
 ### Querying Knowledge
 
 Ask questions naturally: