feat(F-002): database foundation with migrations and dev compose

- node-pg-migrate + pg: baseline migration (extensions, app_meta) with working down
- src/infrastructure/db fail-fast pool and typed query helper
- docker-compose: postgres:16-alpine + redis:7-alpine with one-command up
- table naming convention <module>_<table> documented in README
- integration tests (6) against real PostgreSQL; strict identifier validation
  for test DDL after security-gate hardening round
- deps justified in spec/tech.md; all gates approved; verify.sh green

project/migrations/001_baseline.js

@@ -0,0 +1,25 @@
+/**
+ * Baseline migration: foundation objects only.
+ * Business tables arrive with their owning modules using the
+ * <module>_<table> naming convention.
+ */
+
+/** @param {import('node-pg-migrate').MigrationBuilder} pgm */
+export const up = (pgm) => {
+  pgm.sql('CREATE EXTENSION IF NOT EXISTS citext');
+  pgm.sql('CREATE EXTENSION IF NOT EXISTS pgcrypto');
+  pgm.sql(`
+    CREATE TABLE app_meta (
+      key text PRIMARY KEY,
+      value text NOT NULL,
+      updated_at timestamptz NOT NULL DEFAULT now()
+    )
+  `);
+};
+
+/** @param {import('node-pg-migrate').MigrationBuilder} pgm */
+export const down = (pgm) => {
+  pgm.sql('DROP TABLE IF EXISTS app_meta');
+  pgm.sql('DROP EXTENSION IF EXISTS pgcrypto');
+  pgm.sql('DROP EXTENSION IF EXISTS citext');
+};