## Summary
Refactor the Go `KnowledgeCompilerComponent` so its parameter is a
**single string template id** instead of a DSL-level `variant` (or
plural group id list). The `variant` is no longer in the DSL — it is now
**derived at runtime from the resolved compilation template's `kind`
field**.
This aligns the Go ingestion port with the frontend Compiler operator,
which emits a singular `compilation_template_group_id` and does not
write `variant` into the generated `compiler.json`.
Ports doc-level auto-metadata extraction to Go and adds the
knowledge_compiler component with scheduler/routing. Fixes Extractor
metadata injection type assertion and enable_metadata default-on.
