Fix: PNG images being embedded as binary in local dev (#15457)

In local development, esbuild's write option was set to false, causing
PNG images to be embedded as binary data in the JavaScript output
instead of being written as external files. This resulted in 'Invalid or
unexpected token' errors when rendering pages with images.

Now setting write=true for both development and CI environments, while
keeping it false for production Lambda runtime where the filesystem is
read-only.

Fixes issues multiple developers were experiencing in local dev.

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Co-authored-by: Shannon Anahata <[email protected]>

Author: sfanahata

src/mdx.ts

@@ -685,7 +685,8 @@ export async function getFileBySlug(slug: string): Promise<SlugFile> {
 
       // Set write to false to prevent esbuild from writing files automatically.
       // We'll handle writing manually to gracefully handle read-only filesystems (e.g., Lambda runtime)
-      options.write = !!process.env.CI;
+      // In local dev, we need write=true to avoid images being embedded as binary data
+      options.write = process.env.NODE_ENV === 'development' || !!process.env.CI;
 
       return options;
     },