feat: bootstrap Laravel 13 foundation (Fase 0)

Implement OpenSpec change setup-foundation: Laravel 13 + Filament 5
admin panel, Livewire 4 public site shell, PostgreSQL via Compose,
design tokens, role-based auth, quality gates (Pint/Larastan/Pest),
FrankenPHP Dockerfile, and GitHub Actions CI with five blocking jobs.

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

.editorconfig

@@ -0,0 +1,18 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 4
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false
+
+[*.{yml,yaml}]
+indent_size = 2
+
+[{compose,docker-compose}.{yml,yaml}]
+indent_size = 4