chore: wire PostgreSQL + Prisma per ADR-0006

Add Prisma 7 + nestjs-prisma. The schema lives at
apps/portal-bff/prisma/schema.prisma with provider postgresql; the new
prisma-client generator (Prisma 7 default) outputs the typed client to
apps/portal-bff/generated/prisma/ which is gitignored.

apps/portal-bff/src/app/app.module.ts imports PrismaModule.forRoot
({ isGlobal: true }) so PrismaService is injectable across the BFF
without per-module imports.

apps/portal-bff/.env.example documents DATABASE_URL with a local-dev
default, plus a forward list of env vars introduced by upcoming phases
and ADRs (auth, sessions, MFA, observability, audit, downstream APIs)
- catalog reference, not implementation. The actual .env stays
gitignored at both repo root and app levels.

prisma.config.ts (Prisma 7's TypeScript config) is committed; it loads
DATABASE_URL via dotenv. Schema and migrations paths are pinned to
prisma/ relative to the bff app.

PostgreSQL provisioning, RLS policies for the dual-audience design,
the dedicated audit schema with role grants (audit_owner / audit_writer
/ audit_reader / audit_archiver per ADR-0013), and column-level
encryption for L3-scoped data are out of scope of this commit -
they belong with the future on-prem infrastructure ADR.

apps/portal-bff/.env.example

@@ -0,0 +1,51 @@
+# BFF environment template
+# Copy to .env (which is gitignored) and fill in actual values for local development.
+# Production values are managed by the platform's secret manager (see future infrastructure ADR).
+
+# Postgres connection (per ADR-0006)
+# Local dev default: dockerised Postgres on port 5432, schema 'public'.
+DATABASE_URL="postgresql://portal:portal@localhost:5432/portal_dev?schema=public"
+
+# Future env vars introduced by upcoming phases / ADRs:
+#
+# Auth flow (ADR-0009):
+#   ENTRA_TENANT_ID
+#   ENTRA_CLIENT_ID
+#   ENTRA_CLIENT_SECRET   (or ENTRA_CLIENT_CERT_PATH)
+#   ENTRA_ACCEPTED_TENANT_IDS
+#   ENTRA_REDIRECT_URI
+#   ENTRA_POST_LOGOUT_REDIRECT_URI
+#   SESSION_SECRET
+#
+# Sessions (ADR-0010):
+#   REDIS_URL                       (or REDIS_SENTINEL_HOSTS + REDIS_SENTINEL_NAME)
+#   REDIS_PASSWORD
+#   REDIS_TLS                       ('true' in prod)
+#   SESSION_ENCRYPTION_KEY          (32-byte base64)
+#   SESSION_IDLE_TIMEOUT_SECONDS    (default 1800)
+#   SESSION_ABSOLUTE_TIMEOUT_SECONDS (default 43200)
+#
+# MFA (ADR-0011):
+#   MFA_FRESHNESS_SECONDS           (default 600)
+#
+# Observability (ADR-0012):
+#   LOG_LEVEL                       ('info' in prod, 'debug' in dev)
+#   LOG_USER_ID_SALT                (per-environment salt)
+#   OTEL_SERVICE_NAME               ('portal-bff')
+#   OTEL_SERVICE_VERSION
+#   OTEL_RESOURCE_ATTRIBUTES
+#   OTEL_EXPORTER_OTLP_ENDPOINT
+#   OTEL_EXPORTER_OTLP_PROTOCOL     ('http/protobuf')
+#   OTEL_TRACES_SAMPLER             ('always_on' in v1)
+#
+# Audit trail (ADR-0013):
+#   AUDIT_DATABASE_URL              (separate creds, role 'audit_writer')
+#   AUDIT_ARCHIVER_DATABASE_URL     (role 'audit_archiver', for the retention purge job)
+#   AUDIT_RETENTION_DAYS            (default 365)
+#
+# Downstream API access (ADR-0014):
+#   OBO_CACHE_ENCRYPTION_KEY        (32-byte base64, distinct from SESSION_ENCRYPTION_KEY)
+#   BFF_JWKS_PRIVATE_KEY_PATH
+#   BFF_JWKS_KID
+#   <SERVICE>_API_BASE_URL          (per integrated downstream)
+#   <SERVICE>_TIMEOUT_MS            (optional, defaults to 5000)

apps/portal-bff/.gitignore

@@ -0,0 +1,5 @@
+node_modules
+# Keep environment variables out of version control
+.env
+
+/generated/prisma

apps/portal-bff/prisma.config.ts

@@ -0,0 +1,14 @@
+// This file was generated by Prisma, and assumes you have installed the following:
+// npm install --save-dev prisma dotenv
+import "dotenv/config";
+import { defineConfig } from "prisma/config";
+
+export default defineConfig({
+  schema: "prisma/schema.prisma",
+  migrations: {
+    path: "prisma/migrations",
+  },
+  datasource: {
+    url: process.env["DATABASE_URL"],
+  },
+});

apps/portal-bff/prisma/schema.prisma

@@ -0,0 +1,13 @@
+// This is your Prisma schema file,
+// learn more about it in the docs: https://pris.ly/d/prisma-schema
+
+// Get a free hosted Postgres database in seconds: `npx create-db`
+
+generator client {
+  provider = "prisma-client"
+  output   = "../generated/prisma"
+}
+
+datasource db {
+  provider = "postgresql"
+}

apps/portal-bff/src/app/app.module.ts

@@ -1,9 +1,10 @@
 import { Module } from '@nestjs/common';
+import { PrismaModule } from 'nestjs-prisma';
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
 
 @Module({
-  imports: [],
+  imports: [PrismaModule.forRoot({ isGlobal: true })],
   controllers: [AppController],
   providers: [AppService],
 })