docs-site: annotate imperative SQL, add section anchor, drop ClickHouse

- Wire numbered red badges to each problematic span in the "Without KTX"
  SQL with hover sync between SQL gutter, lines, and the notes list.
- Add #imperative-vs-declarative anchor on the flow section header so
  the eyebrow link is shareable; reveals a # glyph on hover/focus.
- Align the compiled-SQL note dots to the first-line midpoint
  (mt-[6px] instead of mt-1) so 4px dots sit at y=8 in a 16px line.
- Remove all ClickHouse references from docs-site (primary-sources,
  quickstart, ktx-setup, contributing, agents-setup, mechanics test,
  warehouse drivers in the flow diagram).

docs-site/content/docs/community/contributing.mdx

@@ -91,7 +91,6 @@ packages/
   connector-postgres/   # PostgreSQL connector
   connector-snowflake/  # Snowflake connector
   connector-bigquery/   # BigQuery connector
-  connector-clickhouse/ # ClickHouse connector
   connector-mysql/      # MySQL connector
   connector-sqlserver/  # SQL Server connector
   connector-sqlite/     # SQLite connector