Fix curl error handling and add cache cleanup script

[AlexCherrypi]

Fix curl error handling and add cache cleanup script

Bug Fixes in TileProxy.php

1. Fixed curl error checking after curl_close() (critical bug)

   • curl_errno() and curl_error() return invalid data after curl_close() is called
   • Now stores error information before closing the curl handle

2. Added HTTP status code validation

   • Previously only checked for curl transport errors
   • Now also validates HTTP response codes (e.g., 404, 503 from tile servers)
   • Includes response body in error message for debugging

3. Added CURLOPT_FOLLOWLOCATION

   • Some tile servers may redirect requests

4. Fixed double slash in cache paths

   • Changed default paths from ../cache/ to ../cache

New Feature

5. Cache cleanup script (scripts/cleanup-cache.sh)
   • Deletes tiles older than 13 days
   • Limits each style folder to max 1GB (removes oldest files first)
   • Removes empty directories
   • Cron example: 0 3 */5 * * /path/to/cleanup-cache.sh /path/to/cache