0.29.0 — code-quality refactor (plan E1–E5): file splits, sqlc migration, SSH unification, test coverage

E1: split monolithic files — cmd/nomos (main.go → server.go + mcp.go + workers.go),
    internal/mcp/tools.go → entity_tools/ops_tools/knowledge_tools/analysis_tools,
    internal/httpapi/impl.go → domain files (entities, events, signals, ontology,
    fleet_health, client_context, client_lifecycle, entity_mutations, query_audit).
E2: migrate raw pool.Exec queries to sqlc (entities/relationships queries + generated).
E3: unify SSH — consolidate crypto/ssh dial into actuator/client.go (+client_test).
E4/E5: add tests — db/lifecycle, checkdefaults/build, ontology/preconditions, policy/risk.

internal/db/queries/relationships.sql

@@ -25,3 +25,18 @@ ORDER BY r.type, se.slug, te.slug;
 -- name: EndCurrentRelationship :execrows
 UPDATE relationships SET valid_to = now()
 WHERE source_id = $1 AND target_id = $2 AND type = $3 AND valid_to IS NULL;
+
+-- name: InsertRelationshipIfAbsent :execrows
+-- Idempotent relationship insert (the create_relationship surface): no-op if
+-- an active edge of the same source/target/type already exists. Replaces the
+-- raw INSERT...WHERE NOT EXISTS used in entity_tools.go.
+INSERT INTO relationships (source_id, target_id, type, attributes, valid_from)
+SELECT sqlc.arg('source_id'), sqlc.arg('target_id'), sqlc.arg('type'),
+       sqlc.arg('attributes')::jsonb, now()
+WHERE NOT EXISTS (
+    SELECT 1 FROM relationships
+    WHERE source_id = sqlc.arg('source_id')
+      AND target_id = sqlc.arg('target_id')
+      AND type = sqlc.arg('type')
+      AND valid_to IS NULL
+);