- Unify embedding result metadata: replace n_tokens_truncated with a
  shared truncated boolean across local, remote, and custom engines.
- Persist n_tokens and truncated on dbmem_vault and dbmem_cache rows,
  with schema versioning and automatic migration of existing databases.
- Parse the documented vectors.space envelope (output_dimension,
  data[0].embedding, data[0].truncated, usage.request_tokens) instead
  of a flat key scan.
- Add e2e coverage for multi-chunk retrieval and single-chunk inserts
  around the provider token ceiling and model context window; search
  tests print per-chunk n_tokens/truncated round-tripped through the API.
- Run extension unit tests in CI (with local-only build fixes), use
  portable temp paths in sync tests, hash the sync fixture from disk,
  and isolate curl's ./configure from inherited shell build envs.
- Update the C API reference for the truncated flag on custom provider
  results.