chore: reorganize para current/, rails 8.1, testes e readme

- move app para current/ (estrutura capistrano)
- rails 7.2 → 8.1, ruby 3.2, sqlite3 2.x
- adiciona primary_key Idinformativo no model
- schema.rb completo com todas as tabelas
- testes minitest: models (Tag, Informativo, Tema) e controllers
- readme atualizado em pt-br com stack e instruções de desenvolvimento
- gitignore exclui dump.sql, *.duckdb e sqlite3

current/app/admin/admin_users.rb

@@ -0,0 +1,28 @@
+ActiveAdmin.register AdminUser do
+  permit_params :email, :password, :password_confirmation
+
+  index do
+    selectable_column
+    id_column
+    column :email
+    column :current_sign_in_at
+    column :sign_in_count
+    column :created_at
+    actions
+  end
+
+  filter :email
+  filter :current_sign_in_at
+  filter :sign_in_count
+  filter :created_at
+
+  form do |f|
+    f.inputs do
+      f.input :email
+      f.input :password
+      f.input :password_confirmation
+    end
+    f.actions
+  end
+
+end