Publish schema compatibility data

[danielgaskins]

Add a machine-readable schema-compatibility.json alongside the configuration schema and generate the developer-documentation compatibility table from it. The installed schema directory therefore exposes the mapping to downstream tools without requiring them to scrape Markdown.

The documentation workflow now watches schema inputs, and the runtime embed step explicitly includes only the validation schema rather than the new release metadata. This also updates the schema-version check’s stale instruction to point contributors to the changelog.

Tests:

• julia --project=docs docs/generate_schema_compatibility.jl (including idempotence and malformed-entry checks)
• julia --project=docs docs/make.jl
• ./scripts/format-source -jl --dry-run
• generated-schema CMake script check

Closes #833

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[hughcars]

Thanks for the PR @danielgaskins, I tried it out and found a few small issues but the basic idea is a nice way to keep things together.

[Sbozzolo]

LGTM if @hughcars' comments are addressed

[danielgaskins]

Updated this branch from current main and added the Palace 0.18.0 / SchemaVer 1-6-0 release boundary to the compatibility data. The generated table matches the JSON, and the CMake embedding check confirms that the metadata is installed but not embedded as a runtime schema.

[hughcars]

Please add a CHANGELOG entry under In progress as well.