Fix #1554: Configurable base URL with request-optional fallback and v…

[harsh-k7]

Fix #1554: Configurable base URL with request-optional fallback

This PR resolves issue #1554 by introducing a clean way to generate the base URL without requiring an active servlet request context.

Key Changes:

• Added ApplicationConfig with ovsx.server.url and ovsx.webui.url config
• Refactored UrlUtil to use config first and fallback to request
• Added null-safe URL validation and logging
• Works outside servlet context and maintains backward compatibility

This allows API/UI URLs to be configured independently and fixes the original bug.

[harsh-k7]

Fix #1554: Configurable base URL with request-optional fallback and validation