Refactor: Update category structure, mega menu, footer, and remove unused pages

- Move DURGO from ระบบน้ำ to อุปกรณ์ปรับอากาศ
- Add -category suffix to อุปกรณ์ดับเพลิง and ฉนวนหุ้มท่อ category pages
- Update Header mega menu with correct category slugs
- Fix Footer layout: split categories to 2 columns, remove quick links
- Delete unused pages: all-projects, join-us, services, product
- All product images fixed to 1:1 aspect ratio

.gitignore

@@ -13,6 +13,11 @@ node_modules/
 *.log
 npm-debug.log*
 
+# Environment
+.env
+.env.*
+!.env.example
+
 # OS files
 .DS_Store
 Thumbs.db