feat(raw): raw derive reads PDF and Outlook MSG; doctor shows each import filter

PDF is read with pypdf (page markers, scan warning, encrypted files refused), Outlook .msg with olefile as a container like an .eml, and a .msg attached to a mail is quoted. Both packages are in tools/requirements.txt and imported only when such a file is derived, so a missing one stops that format alone. doctor reports one import-filter line per package-backed format.

Files changed:
- CHANGES.md
- VERSION
- docs/how-to/ingest-a-source.md
- docs/reference/commands/instance-health.md
- docs/reference/commands/raw-material-and-uploads.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/commands/doctor.py
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/filters/__init__.py
- tools/chemenu/filters/mail.py
- tools/chemenu/filters/msg.py
- tools/chemenu/filters/pdf.py
- tools/chemenu/tests/binary_formats.py
- tools/chemenu/tests/test_raw_derive_binary.py
- tools/requirements.txt

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

docs/reference/commands/instance-health.md

@@ -28,6 +28,7 @@ tools/wikitool doctor --json
 **Behaviour**
 
 - Checks dependencies (Python, ripgrep), author resolution, stack version, git identity/branch/remote, published skills, the kb/raw/reports/work/instructions structure, and generated files.
+- Import filters (`import-filter-<name>`): one line for each `raw derive` format that reads through a package (PDF, Outlook `.msg`) - a `WARN` naming the package when it is missing, since that costs only its own format; fixed by running `tools/preflight.sh` again.
 - Tool paths (`tool-paths`): `.wikitool-tools.json` written by a preflight that finished, every tool `tools/prerequisites.txt` names for this platform recorded, and every recorded path still there - a `FAIL` otherwise, fixed by running `tools/preflight.sh` again (PowerShell 7: `tools/preflight.ps1`).
 - Install folder (`install-dir`): on Windows with long paths off, a `FAIL` when the folder holding `tools/` is longer than `tools/prerequisites.txt` allows (95 characters) - the limit the preflight enforces before it sets anything up.
 - PowerShell (`execution-policy`, `script-marks`; Windows only, `OK` elsewhere): a `FAIL` when the effective execution policy is `Restricted` or `AllSigned` - the line then says whether a group policy sets it, which only whoever administers the computer can change - and a `FAIL` when a script under `tools/` carries a Mark of the Web from the internet zone, which a browser download unpacked in Explorer leaves behind and `Invoke-WebRequest` plus `tar` do not. `tools/preflight.ps1` checks the same two things before it stops.