feat(db): encrypt Profile health fields at rest (ADR 0002)

Wire prisma-field-encryption AES-256-GCM extension on the shared Prisma
client and annotate the four sensitive columns on Profile with @encrypted:
- weightStartKg / weightCurrentKg / weightGoalKg (Decimal → String)
- targetDate (DateTime @db.Date → String, ISO YYYY-MM-DD)

Other Profile fields stay in clear text per ADR 0002 (age, gender,
heightCm, activityLevel) — they're needed for plan generation and
aggregate analytics, and are not strongly identifying on their own.

apps/api profile.routes.ts:
- serialize() now reads the columns as strings and parses them back to
  numbers for BMR/TDEE; targetDate is already an ISO string from the DB
- the upsert stringifies numeric inputs and slices the date to YYYY-MM-DD

Env wiring:
- packages/db, apps/api, apps/web .env.example all document
  PRISMA_FIELD_ENCRYPTION_KEY (k1.aesgcm256.<base64url>) — must match
  across every process that hits the DB
- key generation snippet documented inline

Migration is intentionally NOT in this commit: needs to be created against
a live Postgres instance and applied. The fields change Decimal/Date → text
so prisma migrate dev will require a USING cast — see the follow-up commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/api/.env.example

@@ -8,6 +8,11 @@ CORS_ORIGINS=http://localhost:3000
 
 DATABASE_URL=postgresql://luciano:luciano%40@localhost:5432/ketopath?schema=public
 
+# Cifratura at-rest dei campi sanitari (vedi ADR 0002).
+# Genera con: node -e "console.log('k1.aesgcm256.'+require('crypto').generateKeySync('aes',{length:256}).export().toString('base64url'))"
+# DEVE coincidere con apps/web/.env e con tutti i deploy che leggono il DB.
+PRISMA_FIELD_ENCRYPTION_KEY=
+
 # Better Auth — DEVE coincidere con apps/web/.env (sessione condivisa)
 BETTER_AUTH_SECRET=
 BETTER_AUTH_URL=http://localhost:3000

apps/api/src/modules/profile/profile.routes.ts

@@ -10,21 +10,24 @@ import type { FastifyPluginAsync } from 'fastify';
 
 import { requireAuth } from '../../plugins/auth.js';
 
+// The weight columns are encrypted at rest (ADR 0002) and therefore stored
+// as String. The Zod input schema parses numeric strings → numbers, but the
+// Prisma row keeps them as strings — so serialize/parse explicitly here.
 function serialize(
   profile: {
     age: number;
     gender: Gender;
     heightCm: number;
-    weightStartKg: { toNumber(): number };
-    weightCurrentKg: { toNumber(): number };
-    weightGoalKg: { toNumber(): number };
+    weightStartKg: string;
+    weightCurrentKg: string;
+    weightGoalKg: string;
     activityLevel: ActivityLevel;
-    targetDate: Date | null;
+    targetDate: string | null;
     currentPhase: string;
   } | null,
 ) {
   if (!profile) return null;
-  const weightCurrentKg = profile.weightCurrentKg.toNumber();
+  const weightCurrentKg = Number(profile.weightCurrentKg);
   const bmr = calculateBmr({
     weightKg: weightCurrentKg,
     heightCm: profile.heightCm,
@@ -36,11 +39,11 @@ function serialize(
     age: profile.age,
     gender: profile.gender,
     heightCm: profile.heightCm,
-    weightStartKg: profile.weightStartKg.toNumber(),
+    weightStartKg: Number(profile.weightStartKg),
     weightCurrentKg,
-    weightGoalKg: profile.weightGoalKg.toNumber(),
+    weightGoalKg: Number(profile.weightGoalKg),
     activityLevel: profile.activityLevel,
-    targetDate: profile.targetDate?.toISOString() ?? null,
+    targetDate: profile.targetDate,
     currentPhase: profile.currentPhase,
     derived: {
       bmr: Math.round(bmr),
@@ -67,6 +70,8 @@ export const profileRoutes: FastifyPluginAsync = async (fastify) => {
     const data = parsed.data;
     const userId = request.user!.id;
 
+    const targetDateStr = data.targetDate ? data.targetDate.toISOString().slice(0, 10) : null;
+
     const profile = await fastify.prisma.profile.upsert({
       where: { userId },
       create: {
@@ -74,21 +79,21 @@ export const profileRoutes: FastifyPluginAsync = async (fastify) => {
         age: data.age,
         gender: data.gender,
         heightCm: data.heightCm,
-        weightStartKg: data.weightStartKg,
-        weightCurrentKg: data.weightCurrentKg,
-        weightGoalKg: data.weightGoalKg,
+        weightStartKg: String(data.weightStartKg),
+        weightCurrentKg: String(data.weightCurrentKg),
+        weightGoalKg: String(data.weightGoalKg),
         activityLevel: data.activityLevel,
-        targetDate: data.targetDate ?? null,
+        targetDate: targetDateStr,
       },
       update: {
         age: data.age,
         gender: data.gender,
         heightCm: data.heightCm,
-        weightStartKg: data.weightStartKg,
-        weightCurrentKg: data.weightCurrentKg,
-        weightGoalKg: data.weightGoalKg,
+        weightStartKg: String(data.weightStartKg),
+        weightCurrentKg: String(data.weightCurrentKg),
+        weightGoalKg: String(data.weightGoalKg),
         activityLevel: data.activityLevel,
-        targetDate: data.targetDate ?? null,
+        targetDate: targetDateStr,
       },
     });
 

apps/web/.env.example

@@ -12,6 +12,10 @@ BETTER_AUTH_URL=http://localhost:3000
 # Database (Better Auth usa @ketopath/db, che legge DATABASE_URL)
 DATABASE_URL=postgresql://luciano:luciano%40@localhost:5432/ketopath?schema=public
 
+# Cifratura at-rest dei campi sanitari (vedi ADR 0002).
+# DEVE essere identica a apps/api/.env.
+PRISMA_FIELD_ENCRYPTION_KEY=
+
 # Google OAuth (configurato a fine progetto)
 # GOOGLE_CLIENT_ID=
 # GOOGLE_CLIENT_SECRET=