stack: MCP submit-Tool mit Upload Review Gate und Quarantäne-Schreibpfad (schliesst #32)

Files changed:
- .gitignore
- AGENTS.md
- CHANGES.md
- INSTALL-MCP.md
- README.md
- VERSION
- docs/why-gates-are-code.md
- instructions/gates.md
- instructions/ingest-queue.md
- instructions/mcp-read-server.md
- instructions/wiki-ingest/SKILL.md
- raw/CONTRACT.md
- tools/CONTRACT.md
- tools/chemenu/cli.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/commands/doctor.py
- tools/chemenu/commands/upload_cmd.py
- tools/chemenu/config.py
- tools/chemenu/mcp/server.py
- tools/chemenu/tests/test_doctor.py
- tools/chemenu/tests/test_mcp_server.py
- tools/chemenu/tests/test_upload.py
- tools/chemenu/tests/test_upload_cmd.py
- tools/chemenu/upload.py

instructions/wiki-ingest/SKILL.md

@@ -60,6 +60,12 @@ validator complains - and the ticked list is the only record that they happened.
    file already in `raw/` skips this step entirely. A subdirectory under `incoming/` (an old
    `incoming/<type>/` habit) is tolerated and ignored - it carries no meaning any more.
 
+   **A file that arrived through the MCP `submit` tool is not yet in `incoming/`** - it sits in
+   `mcp-upload/<id>/`, a quarantine no command in this step reads. A reviewer promotes it first
+   with `wikitool upload accept <id> --confirm <token>`, per
+   [instructions/ingest-queue.md](../ingest-queue.md); once accepted it is an ordinary file in
+   `incoming/` and this step applies to it exactly as to anything dropped there by hand.
+
    **If this refuses because the name is already claimed** (a file stem or a bundle directory
    already occupies the name anywhere under `raw/`), that is not this session's
    call to make: whether the incoming file is a later edition of the existing source or a second,