feat: integrate platform backend and application interfaces

server/migrations/0007_runtime_domain_repository.sql

@@ -0,0 +1,13 @@
+-- Runtime repository projection. Each root is a domain collection and each
+-- row is independently addressable, so PostgreSQL can be promoted from the
+-- legacy snapshot without exposing a JSON blob as the only source of truth.
+CREATE TABLE IF NOT EXISTS miragenflow_domain_rows (
+  root_key TEXT NOT NULL,
+  entity_id TEXT NOT NULL,
+  shape TEXT NOT NULL CHECK (shape IN ('map', 'array', 'scalar')),
+  payload JSONB,
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+  PRIMARY KEY (root_key, entity_id)
+);
+CREATE INDEX IF NOT EXISTS miragenflow_domain_rows_updated_idx
+  ON miragenflow_domain_rows(updated_at DESC);