Remove hash from URLs (/#/login -> /login) using usePathUrlStrategy().
Uses conditional imports to only apply on web, keeping mobile/desktop
builds unaffected.
Required for OIDC callback to work - Authentik redirects to /callback
which Flutter now recognizes as a route.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
