Tech Debt: Minimize the scope of the global error callback

[ericpgreen2]

We have a longstanding global error handler at web-admin/src/features/errors/error-utils.ts. It was originally intended to handle common errors, provide easy-to-read error messages, and cover for the fact that components across the application did not do sufficient error handling themselves. But, this global error handler has long gone too far! We should:

• Throw as many errors as possible in +layout.ts and +page.ts files
• Ensure all major data-intensive components handle their own errors
• Move easy-to-read error messages to a dedicated util function

Pages that don't currently handle their own errors, but should:

• Project
• Organization
• Public URL