feat: INSTALL.md is the English installation tutorial; new tutorial docs/tutorials/first-source-to-first-answer.md with a shipped sample source; README.md links it as its first-ingestion step (#191)

Files changed:
- CHANGES.md
- INSTALL.md
- README.md
- VERSION
- docs/reference/commands/types-instructions-and-docs.md
- docs/tutorials/README.md
- docs/tutorials/first-source-to-first-answer.md
- docs/tutorials/sample-source.md
- instructions/dev/doc-pull-through.md
- tools/CONTRACT.md
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/install_doc.py
- tools/chemenu/tests/test_install_doc.py

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

README.md

@@ -45,7 +45,7 @@ Two starting points, depending on what you're doing:
 The human documentation lives under `docs/`, sorted by what you want from it:
 
 - [docs/tutorials/](docs/tutorials/README.md) - learning: a guided first walk through an
-  instance. Installation is still [INSTALL.md](INSTALL.md).
+  instance, starting with the installation in [INSTALL.md](INSTALL.md).
 - [docs/how-to/](docs/how-to/README.md) - doing: one task per page, for the operator of an
   instance.
 - [docs/reference/](docs/reference/README.md) - looking up: commands, exit codes, skills, page
@@ -61,26 +61,8 @@ How the parts fit together is [docs/explanation/architecture.md](docs/explanatio
 
 ## Your first ingestion
 
-### First Steps
-
-1. Read `AGENTS.md` - the control plane (invariants, routing, gates) - then the stage contract
-   for whichever of `raw/`, `types/` or `kb/` you are working in, and, inside `kb/`, the
-   `COLLECTION.md` of the collection you are writing to
-2. Add your first source to `incoming/`
-3. Run: `Ingest <your-file>`
-4. Review the created pages
-5. Ask your first query
-
-### Example First Ingestion
-
-```bash
-# Add a source
-cp ~/Downloads/my-notes.md incoming/my-notes.md
-
-# Tell the LLM to process it
-# (in your LLM agent)
-Ingest incoming/my-notes.md
-```
+Once the instance runs, [From your first source to your first answer](docs/tutorials/first-source-to-first-answer.md)
+takes a sample document that ships with it through an ingest and a cited answer, step by step.
 
 ## Changelog