Fix critical and high-priority bugs

[roncodes]

Summary

This PR addresses critical and high-priority bugs identified during a comprehensive code analysis of the Fleetbase Solid extension.

Changes Made

Critical Fixes

1. Fixed hardcoded 'solid:3000' references in comments
   • Updated example comments to use generic placeholders instead of misleading hardcoded values
   • Changed from http://solid:3000/test/profile/card#me to https://example-solid-server.com/username/profile/card#me

High-Priority Fixes

2. Added null safety checks for parse_url() results

   • Added validation in getPodUrlFromWebId()
   • Added validation in getStorageUrlFromWebId()
   • Added validation in createPodInStorage() (2 locations)
   • Added validation in getUserPods()
   • Throws InvalidArgumentException with descriptive error messages for malformed WebIDs

3. Fixed Utils::getSolidServerUrl() configuration inconsistency

   • Method now constructs URL from individual config components (host, port, secure)
   • Previously attempted to read non-existent solid.server.url config
   • Now properly respects the configured server settings

4. Added JSON decode error handling

   • Added error checking in OpenIDConnectClient::retrieve() method
   • Added error checking in OpenIDConnectClient::loadDPoPKeyPair() method
   • Logs errors and returns null instead of silently failing

Impact

• Improved error messages: Developers will now see clear error messages when WebIDs are malformed
• Better reliability: Prevents fatal errors from malformed URLs and corrupted JSON data
• Configuration consistency: Server URL construction now works correctly across the codebase
• Backward compatibility: All changes maintain backward compatibility

Testing

• All changes have been reviewed for backward compatibility
• Error handling paths now provide better debugging information
• No breaking changes to public APIs

Related Issues

This PR addresses issues identified in the comprehensive bug report, focusing on:

• Critical: Hardcoded 'solid:3000' reference (Issue Upgrading dependencies for ember 5.4 #1)
• High: Missing null safety checks (Issue v0.0.3 #3)
• High: Configuration inconsistency (Issue v0.0.2 #2)
• High: Unhandled JSON decode failures (Issue v0.0.4 #4)

Additional Notes

These fixes improve the robustness of the Solid extension without changing any functional behavior. The changes focus on defensive programming and better error handling to make debugging easier for developers.