Add dedicated blog image upload config separate from product thumbs.

Introduce MULTER_BLOG_IMAGE_* and VITE_BLOG_IMAGE_* env vars with backend multer helper and CMS config wiring for prod builds.

.env.example

@@ -37,6 +37,9 @@ THROTTLE_LIMIT=120
 MULTER_PRODUCT_THUMB_ALLOWED_MIMES=image/jpeg,image/png
 MULTER_PRODUCT_THUMB_MAX_FILE_BYTES=1048576 # 1MB
 
+MULTER_BLOG_IMAGE_ALLOWED_MIMES=image/jpeg,image/png
+MULTER_BLOG_IMAGE_MAX_FILE_BYTES=1048576 # 1MB
+
 MULTER_SHOP_LOGO_ALLOWED_MIMES=image/jpeg,image/png
 MULTER_SHOP_LOGO_MAX_FILE_BYTES=1048576 # 1MB
 
@@ -135,6 +138,8 @@ VITE_API_BASE_URL=http://localhost:3000/api
 VITE_SHOP_FIAT_CURRENCY=USD
 VITE_PRODUCT_THUMB_ALLOWED_MIMES=image/jpeg,image/png
 VITE_PRODUCT_THUMB_MAX_FILE_BYTES=1048576 # 1MB
+VITE_BLOG_IMAGE_ALLOWED_MIMES=image/jpeg,image/png
+VITE_BLOG_IMAGE_MAX_FILE_BYTES=1048576 # 1MB
 VITE_SHOP_LOGO_ALLOWED_MIMES=image/jpeg,image/png
 VITE_SHOP_LOGO_MAX_FILE_BYTES=1048576 # 1MB
 VITE_SHOP_FAVICON_ALLOWED_MIMES=image/png,image/x-icon,image/vnd.microsoft.icon
@@ -142,6 +147,7 @@ VITE_SHOP_FAVICON_MAX_FILE_BYTES=262144 # 256KB
 VITE_DIGITAL_STOCK_ATTACHMENT_ALLOWED_MIMES=application/pdf,application/zip,image/jpeg,image/png
 VITE_DIGITAL_STOCK_ATTACHMENT_MAX_FILE_BYTES=5242880 # 5MB
 VITE_VALIDATION_PRODUCT_TITLE_MAX_LENGTH=100
+VITE_VALIDATION_BLOG_POST_TITLE_MAX_LENGTH=200
 VITE_VALIDATION_CATEGORY_NAME_MAX_LENGTH=50
 VITE_VALIDATION_DISCOUNT_CODE_MAX_LENGTH=32
 VITE_VALIDATION_VARIANT_IMAGES_MAX=10