### What problem does this PR solve?
Incremental Wiki compilation could lose provenance for claim-light
entities, produce unstable page groups across embedding models, route
entities to unrelated pages, and assign topics without sufficient
page-level context. Document removals and page membership changes could
also leave stale Wiki state.
This PR:
- preserves source document and chunk provenance throughout entity
matching, reduction, page generation, and deletion;
- uses embeddings to retrieve candidates and the LLM to make final page
grouping and incremental routing decisions;
- batches embedding and LLM operations with bounded concurrency and
deterministic fallbacks;
- selects source-scoped topic candidates with embeddings before the page
LLM chooses the final topic;
- rebuilds Wiki state when the compilation mode or embedding model
changes;
- normalizes Wiki array fields returned by the API and retains entities
without relations in graph responses.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
