Add patient personalization: profile saved once, reused every chat turn

apps/auth-service/migrations/002_patient_profile.sql

@@ -0,0 +1,9 @@
+CREATE TABLE IF NOT EXISTS patient_profile (
+    user_id uuid PRIMARY KEY REFERENCES auth_user(id) ON DELETE CASCADE,
+    age_text text,
+    weight_kg numeric,
+    renal_function text,
+    hepatic_function text,
+    known_allergies text,
+    updated_at timestamptz NOT NULL DEFAULT now()
+);