Fix OpenProcessing visualID type mismatch causing rate limiting

[junseok44]

related to #955

Problem

The OpenProcessing API was experiencing 429 rate limiting errors during build due to excessive API calls. Investigation revealed that sketch memoization was failing because of a type mismatch between the API response (visualID: number) and the comparison logic (string).

Changes

• Changed visualID type from string to number
• Removed unnecessary toString() calls in HomepageLayout
• Explicitly convert to string when creating URL parameters (String(sketch.visualID)) to prevent TypeScript from inferring Astro.params.slug as number
• Added centralized type conversion in SketchLayout (const sketchIdNumber = Number(sketchId))
• Updated all OpenProcessing helper functions to accept number parameters (previously string)

I considered two approaches:

1. Keep each function in OpenProcessing.ts accepting string and convert internally to number
2. Convert sketchId to number once in the SketchLayout and have functions accept number as parameters

I went with option 2 because I thought it's more consistent with the visualID type and avoids multiple conversions per function call. Let me know if you think a different approach would be better.

Future Work

Currently, I added basic validation for invalid sketch IDs in SketchLayout.astro:

const sketchIdNumber = Number(sketchId);

if (isNaN(sketchIdNumber)) {
  console.error(`Invalid sketch ID: ${sketchId}`);
}

However, this only logs the error and continues execution, potentially passing NaN to OpenProcessing functions.
I think A follow-up PR should address proper error handling such as:

• Conditional rendering to show error page
• Pre-filtering invalid IDs in getStaticPaths
• Graceful fallback mechanisms....etc

Thanks for reviewing!