feat: add AI catalog description generation

docs/adr/0010-allow-bounded-real-source-samples-for-description-generation.md

@@ -0,0 +1,15 @@
+---
+status: accepted
+---
+
+# Allow bounded real source samples for description generation
+
+Description generation may send up to five real rows and up to five distinct non-null example
+values for relevant columns to the configured model provider, preserving the useful behavior of
+ThothAI. Samples are read only for the current request, treated as untrusted data, bounded before
+prompt construction, and never stored in generation runs, events, or catalog metadata.
+
+This first slice makes that behavior explicit in the UI and operator documentation. A follow-up
+Sensitive Data Policy is required to classify protected fields and exclude or anonymize their
+values before model calls. Until that policy exists, administrators must regard generation as a
+controlled disclosure of sampled source data to the selected provider.