feat(users): add admin-granted verified badge for trusted contributors

- migration 0002: users.verified boolean, default false
- verified rides in the JWT (role + verified claims)
- POST /users/{id}/verify + /unverify, admin-only (403 otherwise)
- Issue now takes the whole user so trust claims travel in the token
- unit + integration + admin-flow tests

users/internal/auth/jwt.go

@@ -5,17 +5,19 @@ import (
 	"time"
 
 	"github.com/golang-jwt/jwt/v5"
-	"github.com/google/uuid"
 
 	"github.com/emil28092005/SciMesh/users/internal/domain"
 )
 
 // Claims is the payload of a signed token. Subject (from RegisteredClaims) is
 // the user id — it becomes the coordinator's jobs.owner_id; Role drives
-// authorization. Both services verify this token locally with the shared HS256
-// secret, so no runtime call back to the userservice is ever needed.
+// authorization; Verified tells the coordinator whether this user's workers are
+// trusted (results accepted without quorum). Both services verify this token
+// locally with the shared HS256 secret, so no runtime call back to the
+// userservice is ever needed.
 type Claims struct {
-	Role domain.Role `json:"role"`
+	Role     domain.Role `json:"role"`
+	Verified bool        `json:"verified"`
 	jwt.RegisteredClaims
 }
 
@@ -35,13 +37,16 @@ func NewIssuer(secret string, ttl time.Duration, now func() time.Time) Issuer {
 	return Issuer{secret: []byte(secret), ttl: ttl, now: now}
 }
 
-// Issue returns a signed token for the user, valid for the configured TTL.
-func (i Issuer) Issue(userID uuid.UUID, role domain.Role) (string, error) {
+// Issue returns a signed token for the user, valid for the configured TTL. It
+// takes the whole user so every trust-bearing field (role, verified) travels in
+// the token, keeping the two services from needing a runtime lookup.
+func (i Issuer) Issue(u *domain.User) (string, error) {
 	now := i.now()
 	claims := Claims{
-		Role: role,
+		Role:     u.Role,
+		Verified: u.Verified,
 		RegisteredClaims: jwt.RegisteredClaims{
-			Subject:   userID.String(),
+			Subject:   u.ID.String(),
 			IssuedAt:  jwt.NewNumericDate(now),
 			ExpiresAt: jwt.NewNumericDate(now.Add(i.ttl)),
 		},