Fix: exclude en/ and site/ from readme/mkdocs auto-generation

The i18n migration introduced en/ and site/ directories, which were being
scanned by getAllMarkdown() and incorrectly mixed into the nav generation.

Changes:
- Add 'en' to ignorePaths: prevents 379 English files from polluting nav
- Add 'site' to ignorePaths: prevents built site artifacts from being scanned

The star difficulty system and README/properdocs.yml generation now only
processes Chinese source files (dishes/, tips/) while respecting the i18n
structure:
- README.md: 385 entries (all Chinese), with star difficulty index
- properdocs.yml: 375 nav entries (dishes + tips), Chinese only
- starsystem/: 358 recipes organized by difficulty (1-5 stars)
- i18n plugin: separate /en/ site built by properdocs, not generated by script

Docker build verified: npm run build → node readme-generate.js ✓
properdocs build with i18n: both zh and en locales ✓

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/readme-generate.js

@@ -7,7 +7,7 @@ const MKDOCS_PATH = 'properdocs.yml';
 const dishesFolder = 'dishes';
 const starsystemFolder = 'starsystem';
 
-const ignorePaths = ['.git', 'README.md', 'node_modules', 'CONTRIBUTING.md', '.github'];
+const ignorePaths = ['.git', 'README.md', 'node_modules', 'CONTRIBUTING.md', '.github', 'en', 'site'];
 
 const categories = {
   vegetable_dish: {