Entrega v1 aula: shell com abas, PITIUPI_HOME e plugins de referência.

Consolida núcleo (presença, peer actions, MessageDispatcher), chat e screencast na galeria, documentação PT-BR e testes JUnit; remove mpChat do catálogo em favor do chat unificado.

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

.gitignore

@@ -1,13 +1,11 @@
 /pitiupi/build/
 /pitiupi/dist/
-/pitiupi/plugins/*.jar
-/pitiupi.chat/build/
-/pitiupi.chat/dist/
-/pitiupi.chat/nbproject/private/
-/pitiupi.screenCast/build/
-/pitiupi.screenCast/dist/
-/pitiupi.mpChat/out/
-/pitiupi.mpChat/dist/
-**/built-jar.properties
-
-.idea/
+/pitiupi/nbproject/private/
+/plugins/chat/build/
+/plugins/chat/dist/
+/plugins/chat/nbproject/private/
+/plugins/screencast/build/
+/plugins/screencast/dist/
+/plugins/screencast/nbproject/private/
+/plugins/mpchat/out/
+/plugins/mpchat/dist/