feat(cli)!: remove fast mode; ktx ingest always builds enriched context (KLO-721) (#237)

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).

AGENTS.md

@@ -350,8 +350,9 @@ error messages — including the disambiguation rule for the overloaded word
 `source` (semantic / primary / context / source of truth) — see
 [`docs/terminology.md`](docs/terminology.md). Follow that file when choosing
 between near-synonyms (e.g. `connector` vs `adapter`, `data agent` vs
-`database agent`, `fast ingest` vs `schema ingest`). Product-name rules in
-this section take precedence over anything in that file when they conflict.
+`database agent`, `context-source ingest` vs `source ingest`). Product-name
+rules in this section take precedence over anything in that file when they
+conflict.
 
 ### Updating `docs-site/` After Code Changes