feat(api): identité user-first — login/password, ownership user, fin du token device

- 000006 : users.username/username_normalized/password_hash/is_admin, index
  unique partiel sur username_normalized, DROP idx_users_email (unicité V1 =
  username, jamais email) ; 000007 destructif : resources.owner_id→user_id
  (FK→users, reset base dev), l'unicité racine devient par user
- pkg/passwd : argon2id (t=1,m=64MiB,p=4,k=32), comparaison constant-time,
  VerifyTimedEqual (délai égalisé dummy-hash) ; pkg/auth : subject=user_id +
  claim device_id, TTL 7 j sans refresh
- repository : Users (count/get/resolve-exact/create/update-password/
  mark-deleted), Devices.MarkUser (user_id INFORMATIF uniquement)
- handlers : POST /devices sans token, POST /auth/login (401 indistinguable
  user inconnu/mauvais mdp, device requis), PATCH /users/me/password
  (current_password, tokens non révoqués — limite V1), GET /users/resolve
  (exact lowercase, jamais email/is_admin) ; middleware RequireAuth
  (user authorisant, device porté) ; tout le scoping ressources passe user
- bootstrap admin : users vide + ADMIN_* absents → refus de démarrer ;
  .env.example ; docs/api-v1.md §2/§3/§7/§8
- tests : migrations 000006/000007 (up/down), pkg/auth Identity, handlers
  login/password/resolve, helpers refactorés registerAndLogin, repo tests
  scopés user — suite backend verte

backend/handlers/middleware.go

@@ -1,39 +1,64 @@
 package handlers
 
 import (
+	"errors"
+	"net/http"
 	"strings"
 
 	"github.com/gin-gonic/gin"
 	"github.com/vaultdrop/backend/pkg/api"
 	"github.com/vaultdrop/backend/pkg/auth"
+	"github.com/vaultdrop/backend/repository"
 )
 
-const DeviceIDKey = "device_id"
+const (
+	UserIDKey   = "user_id"
+	DeviceIDKey = "device_id"
+)
 
 // Auth issues/verifies device bearer tokens; set once at startup (cmd/server).
 var Auth *auth.Manager
 
-// RequireDevice authenticates the bearer paseto token and stores the resolved
-// device_id in the gin context (cf. docs/api-v1.md §2).
-func RequireDevice(c *gin.Context) {
+// RequireAuth authenticates the bearer paseto token. Le subject (user_id)
+// autorise — c'est la clé de scoping de toutes les ressources ; device_id est
+// porté (non autorisant) pour l'idempotence outbox et les jobs OCR. Le compte
+// doit encore exister (cf. docs/api-v1.md §2).
+func RequireAuth(c *gin.Context) {
 
 	header := c.GetHeader("Authorization")
 	token, found := strings.CutPrefix(header, "Bearer ")
 
 	if Auth == nil || !found || token == "" {
-		api.Error(c, 401, "UNAUTHORIZED", "missing bearer token")
+		api.Error(c, http.StatusUnauthorized, "UNAUTHORIZED", "missing bearer token")
 		c.Abort()
 		return
 	}
 
-	deviceID, err := Auth.Verify(token)
+	identity, err := Auth.Verify(token)
 	if err != nil {
-		api.Error(c, 401, "UNAUTHORIZED", "invalid or expired token")
+		api.Error(c, http.StatusUnauthorized, "UNAUTHORIZED", "invalid or expired token")
 		c.Abort()
 		return
 	}
 
-	c.Set(DeviceIDKey, deviceID)
+	// Le store peut être nil dans les tests middleware purs ; sinon on vérifie
+	// que le compte existe toujours (supprimé → accès refusé).
+	if Store != nil && Store.Repository != nil {
+		_, err := Store.Repository.Users.GetByID(identity.UserID)
+		if errors.Is(err, repository.ErrNotFound) {
+			api.Error(c, http.StatusUnauthorized, "UNAUTHORIZED", "account no longer exists")
+			c.Abort()
+			return
+		}
+		if err != nil {
+			api.Error(c, http.StatusInternalServerError, "INTERNAL", "could not load account")
+			c.Abort()
+			return
+		}
+	}
+
+	c.Set(UserIDKey, identity.UserID)
+	c.Set(DeviceIDKey, identity.DeviceID)
 	c.Next()
 
 }