Rename project to SSAU Generator and restructure content

- Move projects into content/<project>/{docx,pptx} with shared assets/
- Flatten config paths; output = project name in project folder
- Add pptx --init scaffold; remove docx exe build
- Add feature-complete content/example; ignore content/* except example
- Rewrite README and AGENTS.md

docx/src/config/validate.js

@@ -69,6 +69,9 @@ function validateConfig(config) {
   if (!(typeof typography.lineSpacing === 'number' && typography.lineSpacing > 0)) {
     errors.push('typography.lineSpacing: ожидалось положительное число');
   }
+  if (typography.language != null && typeof typography.language !== 'string') {
+    errors.push('typography.language: ожидалась строка (например, ru-RU)');
+  }
 
   for (const [key, value] of Object.entries(page.margins)) {
     if (!Number.isInteger(value) || value < 0) {