Wire the guarded conversational RAG answer layer end-to-end

apps/ai-service/migrations/001_rag_retrieval_trace.sql

@@ -0,0 +1,14 @@
+CREATE TABLE IF NOT EXISTS rag_retrieval_trace (
+    trace_id uuid PRIMARY KEY,
+    query_text text NOT NULL,
+    subject_scope text NOT NULL,
+    query_intent text NOT NULL,
+    decision text NOT NULL,
+    reason text NOT NULL,
+    resolved_drug_id text,
+    citations jsonb NOT NULL DEFAULT '[]'::jsonb,
+    created_at timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE INDEX IF NOT EXISTS rag_retrieval_trace_created_at_idx
+    ON rag_retrieval_trace (created_at DESC);