Aggiunge gestione account con cambio password su web e app.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/users/change_password.rb

@@ -0,0 +1,39 @@
+module Users
+  class ChangePassword
+    Result = Struct.new(:ok?, :error, keyword_init: true)
+
+    def self.call(user:, current_password:, password:, password_confirmation:)
+      new(
+        user: user,
+        current_password: current_password,
+        password: password,
+        password_confirmation: password_confirmation
+      ).call
+    end
+
+    def initialize(user:, current_password:, password:, password_confirmation:)
+      @user = user
+      @current_password = current_password.to_s
+      @password = password.to_s
+      @password_confirmation = password_confirmation.to_s
+    end
+
+    def call
+      unless @user.authenticate(@current_password)
+        return Result.new(ok?: false, error: :current_incorrect)
+      end
+
+      if @password.blank? || @password.length < 8
+        return Result.new(ok?: false, error: :too_short)
+      end
+
+      if @password != @password_confirmation
+        return Result.new(ok?: false, error: :mismatch)
+      end
+
+      @user.update!(password: @password)
+      @user.clear_password_reset!
+      Result.new(ok?: true)
+    end
+  end
+end