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

.gitignore

@@ -1,6 +1,6 @@
 # Chemenu - .gitignore
 #
-# Rule for this file: `raw/`, `kb/` and `work/` are the repository's content, and
+# Rule for this file: `raw/`, `kb/`, `work/` and `sites/` are the repository's content, and
 # a pattern that silently excludes one of their files is a data-loss bug - the
 # wiki keeps reporting the file as covered while `publish` never commits it.
 # So:
@@ -193,9 +193,10 @@ npm-debug.log*
 # `incoming/`.
 /mcp-upload/
 
-# Content backstop - keep this block last. Nothing under raw/, kb/ or work/ may
+# Content backstop - keep this block last. Nothing under raw/, kb/, work/ or sites/ may
 # be excluded by a pattern above; see the header note for why directory patterns
 # still have to be anchored rather than relying on these negations.
 !raw/**
 !kb/**
 !work/**
+!sites/**