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

tools/CONTRACT.md

@@ -1515,7 +1515,7 @@ Derive reading text from a PDF, e-mail, Office file or web page in `incoming/`,
 - A single file directly in `incoming/` becomes a folder named after its stem (or `--name`) holding `original.<ext>` - the original bytes, moved - and `derived.md`. The fixed names keep the path inside the path budget; the header of `derived.md` records the file's own name as `original_name`.
 - A folder is derived in place: each file with a filter gets `<stem>.md` beside it, nothing is renamed, and the files without a filter are named in the output.
 - `derived.md` starts with a fixed header (`derived_by`, `filter`, `engine`, `derived`, `derived_from`, `original_name` for a renamed file, `title`, then the fields of the format) followed by the derived text. The same bytes always give the same text; only `derived` differs between runs. `engine` names the tool version and, where a package reads the format, its version.
-- Formats: web pages (`.html`), Word (`.docx`), PowerPoint (`.pptx`), Excel (`.xlsx`, `.xlsm`), e-mail (`.eml`) and ZIP archives (`.zip`), read with the standard library only.
+- Formats: web pages (`.html`), Word (`.docx`), PowerPoint (`.pptx`), Excel (`.xlsx`, `.xlsm`), e-mail (`.eml`) and ZIP archives (`.zip`), read with the standard library only; PDF (`.pdf`, `pypdf`) and Outlook messages (`.msg`, `olefile`), each read by a package in `tools/requirements.txt` that is imported only when such a file is derived. A missing package refuses that format alone, with the preflight hint; `wikitool doctor` shows one `import-filter-<name>` line per package-backed format. A PDF gets `<!-- page N -->` markers and a WARN when it yields almost no text (a scan; there is no OCR); an encrypted PDF is refused. A `.msg` is a container like an `.eml`; an embedded message inside it is named, not read.
 - A ZIP and a mail are containers. A ZIP at the top of `incoming/` becomes the folder `incoming/<stem>/` holding its files under their own names, each with a `<stem>.md` where a filter reads it; the ZIP is removed and the output names it with its sha256. A mail becomes a folder with `original.eml`, `derived.md` and its attachments under their own names; a ZIP attached to it is unpacked once into a folder of its own, and an attached mail is quoted in `derived.md`, not unpacked. A ZIP inside a ZIP, an absolute or `..` path, a symbolic link, an encrypted entry, more than 1000 entries, a file over 25 MiB or more than 250 MiB in total refuse the whole call. Hidden entries (`__MACOSX/`, `.DS_Store`, anything starting with a dot) are named, not written. A name taken twice, or reserved (`original.*` and `derived.md` at the top of a mail's folder, `_capture.json` anywhere), gets `-2`, `-3` before its extension, and the output lists each rename.
 - A name already taken under `raw/` is a WARN, not a refusal: whether the folder is a later edition of that source or a separate one is the human's call. A later edition of a derived source is replaced file by file with `raw accept --replaces`; there is no `--replaces-bundle` for it.
 - After a success the output prints the warnings the filters raised, at most three `CHECK` lines per format that was derived in this run - what to look at before the text is trusted - and the `raw accept` line for the result.
@@ -3692,6 +3692,7 @@ Check that this instance is correctly configured.
 **NOTES**
 
 - 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.