v0.5.0 — Better Zarr manifest caching

• Reduced the sizes of a number of streams & futures
• Added doc comments to much of the code
• Return 502 status when a backend returns an invalid response
• Require --api-url (and other URLs retrieved from APIs) to be HTTP(S)
• Added various developer-facing documents to the repository
• Format all log lines as JSON
• Add logging of Zarr manifest cache events
• Limit Zarr manifest cache by total size of entries
  • Add a -Z/--zarrman-cache-mb option for setting the cache size
• Expire idle Zarr manifest cache entries
• Log Zarr manifest cache entries every hour
• Increased MSRV to 1.78