feat(connections): add execute-only warehouses; stop silent full-project scans

A configured warehouse was always a scan/ingest target. The only way to use a
connection purely for SQL execution (ktx sql / sql_execution) was the leaky
workaround of an empty setup.database_connection_ids — which actually re-includes
every warehouse via the 'fall back to all' branch — so e.g. a BigQuery connection
meant only for read-only queries triggered a full-billing-project scan.

- Add a per-connection scan_enabled flag (default true) to warehouse connections.
  scan_enabled: false registers the connection for execution only and never as a
  scan target.
- Route every scan-target selection path through one predicate
  (isScanTargetWarehouse): both ingest (primaryWarehouseConnectionIds, including
  the all-warehouses fallback) and setup (configuredPrimaryConnectionIds) now
  exclude execute-only connections. Setup validates the credential but skips
  scope discovery and scan for them. Execution paths are untouched — the warehouse
  descriptor still resolves, so ktx sql / sql_execution keep working.
- Scripted setup with no --database-schema no longer silently scopes the scan to
  every discovered schema/dataset: it warns with the count and names how to narrow
  (--database-schema) or opt out (scan_enabled: false).

packages/cli/test/context/connections/local-warehouse-descriptor.test.ts

@@ -1,10 +1,32 @@
 import { describe, expect, it } from 'vitest';
 import {
+  isExecuteOnlyConnection,
+  isScanTargetWarehouse,
   localConnectionInfoFromConfig,
   localConnectionToWarehouseDescriptor,
   localConnectionTypeForConfig,
 } from '../../../src/context/connections/local-warehouse-descriptor.js';
 
+describe('execute-only warehouse connections', () => {
+  it('treats a warehouse without scan_enabled as a scan target', () => {
+    const connection = { driver: 'postgres', url: 'postgresql://db/a' } as const;
+    expect(isExecuteOnlyConnection(connection)).toBe(false);
+    expect(isScanTargetWarehouse('w', connection)).toBe(true);
+  });
+
+  it('excludes a warehouse with scan_enabled: false from scan targets but still resolves it as a warehouse', () => {
+    const connection = { driver: 'postgres', url: 'postgresql://db/a', scan_enabled: false } as const;
+    expect(isExecuteOnlyConnection(connection)).toBe(true);
+    expect(isScanTargetWarehouse('w', connection)).toBe(false);
+    // Execution paths must still see it as a warehouse so `ktx sql` works.
+    expect(localConnectionToWarehouseDescriptor('w', connection)).not.toBeNull();
+  });
+
+  it('does not treat non-warehouse connections as scan targets', () => {
+    expect(isScanTargetWarehouse('n', { driver: 'notion', auth_token: 'x' } as never)).toBe(false);
+  });
+});
+
 describe('localConnectionToWarehouseDescriptor', () => {
   it('maps local Postgres URLs to canonical warehouse descriptors', () => {
     expect(

packages/cli/test/context/ingest/local-adapters.test.ts

@@ -634,6 +634,21 @@ describe('local ingest adapters', () => {
     await expect(adapter?.listTargetConnectionIds?.('/tmp/staged-dbt')).resolves.toEqual(['warehouse']);
   });
 
+  it('excludes execute-only (scan_enabled: false) warehouses from primary scan targets', async () => {
+    const adapters = createDefaultLocalIngestAdapters(
+      projectWithConnections({
+        scannable: { driver: 'postgres', url: 'postgresql://db/a' },
+        executeonly: { driver: 'postgres', url: 'postgresql://db/b', scan_enabled: false },
+        docs: { driver: 'dbt', source_dir: './dbt' },
+      } as never),
+    );
+
+    // No setup.database_connection_ids → falls back to "all warehouses", which must now
+    // skip the execute-only connection rather than re-including it.
+    const dbt = adapters.find((adapter) => adapter.source === 'dbt');
+    await expect(dbt?.listTargetConnectionIds?.('/tmp/staged-dbt')).resolves.toEqual(['scannable']);
+  });
+
   it('passes primary warehouse connection ids to the local Notion adapter', async () => {
     const adapters = createDefaultLocalIngestAdapters(
       projectWithConnections({

packages/cli/test/context/project/config.test.ts

@@ -129,6 +129,18 @@ connections:
     expect(serialized).not.toContain('completed_steps:');
   });
 
+  it('parses and serializes a warehouse connection marked execute-only (scan_enabled: false)', () => {
+    const config = parseKtxProjectConfig(`
+connections:
+  public_bq:
+    driver: bigquery
+    scan_enabled: false
+`);
+
+    expect(config.connections.public_bq).toMatchObject({ driver: 'bigquery', scan_enabled: false });
+    expect(serializeKtxProjectConfig(config)).toContain('scan_enabled: false');
+  });
+
   it('parses global direct Anthropic LLM config', () => {
     const config = parseKtxProjectConfig(`
 llm: