tools: raw_cmd.py split into the package commands/raw/, one module per subcommand (#206)

Pure restructuring: every raw subcommand's output, help text and exit code is unchanged; the shared helpers sit in raw/_common.py.

Files changed:
- CHANGES.md
- VERSION
- tools/README.md
- tools/chemenu/cli.py
- tools/chemenu/commands/raw/__init__.py
- tools/chemenu/commands/raw/_common.py
- tools/chemenu/commands/raw/accept.py
- tools/chemenu/commands/raw/capture.py
- tools/chemenu/commands/raw/derive.py
- tools/chemenu/commands/raw/fetch.py
- tools/chemenu/commands/raw/pending.py
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/tests/test_docs_verify.py
- tools/chemenu/tests/test_export_guidelines.py
- tools/chemenu/tests/test_raw_capture.py
- tools/chemenu/tests/test_raw_cmd.py
- tools/chemenu/tests/test_raw_derive.py
- tools/chemenu/tests/test_raw_derive_testfiles.py
- tools/chemenu/tests/test_raw_fetch.py
- tools/chemenu/upload.py

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

tools/README.md

@@ -119,7 +119,7 @@ tools/
     guideline_export.py    `export guidelines`' core: select pages by `search` predicates, render them into one deterministic GUIDELINES.md, and recognise an export again (`EXPORT_MARKER`) - with no CLI attached
     search/                pluggable search backends, plus service.py - the search core
     tasks/                 the task-tracker provider layer: protocol.py (TaskReader/TaskWriter), config.py (.wikitool-tasks.json), one module per adapter - no instruction ever learns which provider it is
-    commands/              one module per command or command group: the terminal adapters
+    commands/              one module per command or command group: the terminal adapters - except `raw/`, a package with one module per subcommand and the helpers several of them share in `_common.py`
     tests/                 pytest suite - origin repository only, `dist export` leaves it out
 ```