feat(raw): raw derive turns Office files and mail into a folder with the original and a derived text

Adds the import-filter registry (tools/chemenu/filters), the raw derive command with folder form,
path-budget and name checks, DOCX/PPTX/XLSX and EML filters, the pending and accept hints, the
wiki-ingest skill step and the raw/CONTRACT.md section. First of three cuts; containers and
PDF/MSG follow.

Files changed:
- CHANGES.md
- VERSION
- docs/how-to/ingest-a-source.md
- docs/reference/commands/README.md
- docs/reference/commands/raw-material-and-uploads.md
- instructions/wiki-ingest/SKILL.md
- raw/CONTRACT.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/cli_contract.py
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/filters/__init__.py
- tools/chemenu/filters/html_page.py
- tools/chemenu/filters/mail.py
- tools/chemenu/filters/ooxml.py
- tools/chemenu/tests/test_raw_derive.py
- tools/chemenu/web_capture.py

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

docs/reference/commands/README.md

@@ -79,6 +79,7 @@ Full records: [provenance.md](provenance.md)
 Full records: [raw-material-and-uploads.md](raw-material-and-uploads.md)
 
 - [`raw fetch`](raw-material-and-uploads.md#raw-fetch) - Capture a web page the user names into `incoming/`: the HTML as received plus a derived text, for `raw accept` to promote.
+- [`raw derive`](raw-material-and-uploads.md#raw-derive) - Derive reading text from a PDF, e-mail, Office file or web page in `incoming/` and leave the original beside it, for `raw accept` to promote.
 - [`raw capture`](raw-material-and-uploads.md#raw-capture) - Capture documentation from a git repository into `incoming/<bundle>/`, with a manifest naming the repository, ref rule and commit, for `raw accept` to promote.
 - [`raw status`](raw-material-and-uploads.md#raw-status) - Report which captured bundles under `raw/` have fallen behind their repository, with each changed file as `A`/`M`/`D`.
 - [`raw pending`](raw-material-and-uploads.md#raw-pending) - List what waits in `incoming/`, oldest first, and name the entry an ingest without an argument takes next.