feat(raw): raw derive unpacks ZIP archives and mails with attachments into a folder

A ZIP becomes incoming/<stem>/ with its files and a derived text beside each
document, the ZIP is removed and its sha256 named in the output. A mail with
attachments becomes a folder with original.eml, derived.md and the attachments;
a ZIP attached to a mail is unpacked once, an attached mail is quoted. Unsafe
entries, nested ZIPs and size limits are refused before anything is written.

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
- raw/CONTRACT.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/filters/__init__.py
- tools/chemenu/filters/archive.py
- tools/chemenu/filters/mail.py
- tools/chemenu/tests/test_portability.py
- tools/chemenu/tests/test_raw_derive.py

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

VERSION

@@ -1 +1 @@
-9.0.0-beta.14
+9.0.0-beta.15