feat(cli)!: remove fast mode; ktx ingest always builds enriched context (KLO-721)

Fast mode (the ktx ingest --fast/--deep database-ingest depth toggle) is removed.
ktx ingest now always builds the full enriched ("deep") context. There is no
structural fallback: a database connection without a configured model and
embeddings fails the enrichment-readiness preflight before any work runs, with
a 'Run ktx setup to configure a model and embeddings' hint.

- Remove --fast/--deep flags, the per-connection context.depth field, and the
  ktx setup depth prompt (delete setup-database-context-depth.ts).
- Rename ingest-depth.ts -> connection-drivers.ts; ingest always requests scan
  mode 'enriched'; readiness gate (enrichmentReadinessGaps) runs for every
  database target.
- Drop the database-context-depth telemetry step (Node + Python schema mirrors
  regenerated).
- Update CLI, setup, context-build view, docs, the public ktx skill, and the
  release-smoke / artifacts scripts (now assert the no-LLM guard failure).

ktx status --fast (a separate network-probe flag) is unchanged.

Follow-ups: KLO-726 (live progress for ktx ingest --all), KLO-727 (restore
credentialed successful-ingest release smoke coverage).

docs-site/content/docs/cli-reference/ktx-setup.mdx

@@ -131,8 +131,8 @@ BigQuery; and `databases` for ClickHouse.
 Query history setup is supported for Postgres, BigQuery, and Snowflake. The
 window flag applies to BigQuery and Snowflake; Postgres reads the current
 `pg_stat_statements` aggregate data instead of a time-windowed history table.
-Enabling query history makes deep ingest readiness matter for later
-`ktx ingest` runs.
+Later `ktx ingest` runs build enriched context and need a configured model and
+embeddings, including when query history is enabled.
 
 When query history is enabled for PostgreSQL, Snowflake, or BigQuery,
 `ktx setup` runs a non-blocking readiness probe after the connection test