sites: the instance writes its own site handlers as JSON files under sites/, the stack's learn.microsoft.com handlers become data files in the same format (#210); 10.0.0-beta.4

Files changed:
- .gitignore
- AGENTS.md
- CHANGES.md
- VERSION
- docs/explanation/architecture.md
- docs/how-to/README.md
- docs/how-to/write-a-site-handler.md
- docs/reference/commands/instance-health.md
- docs/reference/commands/raw-material-and-uploads.md
- docs/reference/configuration.md
- instructions/dev/doc-pull-through.md
- raw/CONTRACT.md
- sites/CONTRACT.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/commands/doctor.py
- tools/chemenu/commands/git_publish.py
- tools/chemenu/commands/raw/fetch.py
- tools/chemenu/ownership.py
- tools/chemenu/sites/__init__.py
- tools/chemenu/sites/data.py
- tools/chemenu/sites/handlers/learn-microsoft-powershell-module.json
- tools/chemenu/sites/handlers/learn-microsoft.json
- tools/chemenu/sites/learn_microsoft.py
- tools/chemenu/sites/site.schema.json
- tools/chemenu/tests/test_dist_cmd.py
- tools/chemenu/tests/test_doctor.py
- tools/chemenu/tests/test_site_files.py
- tools/chemenu/toc.py

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

docs/reference/commands/instance-health.md

@@ -43,6 +43,7 @@ tools/wikitool doctor --json
 - Settings (`settings-instance`, `settings-checkout`, `settings-secrets`): one line per tier. `wikitool.json` and `.wikitool-local.json` each present or absent - absent is `OK` - and a `FAIL` naming file, key and the right tier when a value sits in the wrong file, a secret or a committed private field holds a plain value, or a value fails its field; a section this version does not read is a `WARN`. For the references: how many resolve, never a value - an unresolvable one is a `FAIL`, one 1Password will not hand out until a human unlocks it a `WARN`.
 - Session id source: `OK` for `WIKITOOL_SESSION_ID` or a registered harness variable, `WARN` only for the bare parent-pid fallback.
 - Telemetry: on or off and why - installation-form default, the `telemetry` section of `.wikitool-local.json`, or `WIKI_TRACE` - and the current session's count and byte total against both caps; never a `FAIL`. A `WARN` when that section is not read as written - unreadable JSON, not an object, `enabled` not a JSON boolean, a cap not a positive integer, or an unknown key - naming the field; telemetry itself drops or reinterprets such a value without a word, so this is where it shows.
+- Site handlers (`site-handlers`): every file in `sites/` is read against the handler schema and the rules the schema cannot state; `FAIL` for a file that cannot be used, naming the file and the reason, and `OK` listing the instance's handlers, each one that replaces a stack handler (the same host and path) named as such.
 - Exits 1 only on a `FAIL`; a missing remote, session id or `VERSION` is a `WARN`, not a fault.
 - Read-only and exempt from the Iteration Budget Gate.