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/agents-setup.md

@@ -53,7 +53,7 @@ Ask the user (grouped if your harness supports it; otherwise sequentially):
 3. **Embeddings backend.** Default: `sentence-transformers` (local, no API key, managed Python runtime). Offer `openai` only if the user has a key.
 4. **Database connections.** Ask how many to add, then loop. For each, collect:
    - Connection name (e.g. `warehouse`, `analytics`).
-   - Driver: one of `sqlite`, `postgres`, `mysql`, `clickhouse`, `sqlserver`, `bigquery`, `snowflake`.
+   - Driver: one of `sqlite`, `postgres`, `mysql`, `sqlserver`, `bigquery`, `snowflake`.
    - Connection URL/DSN (or service-account file for BigQuery). Accept `env:VAR_NAME` or `file:/abs/path` to avoid pasting raw secrets.
      - **Heads-up for the user**: even if they paste a literal URL, KTX will silently relocate it into `<project>/.ktx/secrets/<connection>-url` and rewrite `ktx.yaml` to `url: file:…` — this is correct, secure behavior and not a bug.
    - Schemas / datasets to include (postgres / sqlserver / snowflake / bigquery only).