kg: refactor published-concepts-query.js to SELECT.from(PublishedConcepts) #684

Follow-up from PR #679 (Phase 3 Track 3-A, code-review finding).

Context

srv/lib/published-concepts-query.js currently selects from Concepts directly with the publish gate (publishedAt IS NOT NULL AND status='ACTIVE') inlined into the WHERE clause:

const published = await db.run(
  SELECT.from(Concepts)
    .columns('ID', 'slug', 'name', 'description')
    .where({ publishedAt: { '!=': null }, status: 'ACTIVE' })
    .orderBy('slug')
)

The same predicate is declared by the PublishedConcepts CDS view in srv/knowledge-graph-service.cds. This is functionally correct but duplicates the gate predicate in two places. The view exists primarily as an admin-readable surface but the runtime helper duplicates it.

Change

Switch the helper to read from PublishedConcepts:

const { PublishedConcepts } = entities('com.sap.developers.ims')  // adjust namespace if needed
const published = await db.run(
  SELECT.from(PublishedConcepts)
    .columns('ID', 'slug', 'name', 'description')
    .orderBy('slug')
)

Validate that:

• The existing unit tests in test/unit/srv/published-concepts-query.test.js still pass.
• The unit-test fixture's in-memory SQLite deploy actually surfaces PublishedConcepts (CDS views may behave differently in SQLite vs HANA — verify the test setup deploys it).

Acceptance

• Helper selects from PublishedConcepts (no WHERE clause needed).
• All 7 unit tests in published-concepts-query.test.js still pass.
• Single source of truth for the publish gate: the CDS view definition.

Refs

• PR feat(kg): Phase 3 Track 3-A — concept landing pages (#446) #679 (parent — landed the duplicated predicate intentionally)
• Spec: docs/superpowers/specs/2026-06-27-446-knowledge-graph-phase3-design.md §2.2