docs: complete SQL reference, enrich Functions drafts, rename OSS to Embedded (#4732)

## Summary

- Complete the SQL reference: `ATTACH DATABASE`, the `CHANGES` clause,
and
`dedupe()`/`duplicate_pairs()` (verified against current sophon source;
these were recently renamed from
`vector_dedup`/`vector_duplicate_pairs`).
  Fix the blob-column default-projection claim and add the previously
  undocumented `blob_descriptor()`.
- Enrich the gated Functions draft (still `.mintignore`'d, pre-release):
  chained Functions over blob outputs, GPU-produced blobs, Secrets,
  multi-input/output binding, `code=[module]` packaging.
- Upgrade the materialized-view and computed-column auto-refresh drafts
with
  precise, verified catch-up semantics, and add the missing `ALTER
  MATERIALIZED VIEW` / `CREATE ... WITH(...)` sections (also gated — the
  automatic-refresh scheduler is still dev/staging-only).
- Thread one running example (video frames → GPU extract/caption → dedup
→
auto-refreshing materialized view) through Functions, materialized
views,
and the LeRobotDataset integration guide instead of a separate tutorial.
- Rename "LanceDB OSS"/"OSS" to "LanceDB Embedded"/"Embedded" throughout
  (52 files); activate the existing availability-comparison mechanism on
  `basics/offerings.mdx` for a full feature-by-feature comparison table.

docs/web/sql/dml/delete.mdx

@@ -4,10 +4,11 @@ sidebarTitle: "Delete"
 description: "DELETE FROM ... WHERE: rows are marked, not erased."
 icon: trash
 keywords: ["delete", "sql"]
+availability:
+  embedded: unavailable
+  enterprise: available
 ---
 
-<Badge color="red">Enterprise</Badge> [SQL runs in LanceDB Enterprise.](/sql)
-
 ```sql
 DELETE FROM documents WHERE created_at < TIMESTAMP '2025-01-01 00:00:00'
 ```