Fix Go build errors in quota and auth modules

[JoshuaAFerguson]

Fixed the following compilation errors in the API codebase:

1. UserQuota model fields (internal/quota/enforcer.go):

   • Fixed type mismatch between UserQuota/GroupQuota models (string fields) and Limits struct (int64 fields)
   • Added proper parsing of Kubernetes resource quantities (MaxCPU, MaxMemory, MaxStorage)
   • Updated GetUserLimits to parse string quota values from database models

2. SAML authentication (internal/auth/saml.go, handlers.go):

   • Added GetServiceProvider() method to SAMLAuthenticator for metadata endpoint
   • Added ExtractUserFromAttributes() method to work with samlsp.Attributes map
   • Fixed metadata XML serialization in handlers (added xml.Marshal)
   • Added missing imports: encoding/xml, fmt

3. OIDC authentication (internal/auth/oidc.go):

   • Added missing crypto/tls import for TLS configuration

4. Middleware (internal/auth/middleware.go):

   • Removed unused context import

5. Compression middleware (internal/middleware/compression.go):

   • Fixed function signature: changed *gin.Context.Request to *http.Request
   • Added missing net/http import

6. Input validation middleware (internal/middleware/inputvalidation.go):

   • Fixed variable shadowing in sanitizeMap and sanitizeArray methods
   • Changed switch variable from 'v' to 'val' to avoid shadowing receiver

All application code errors are now resolved. Remaining k8s.io/apimachinery dependency issue is an upstream compatibility problem between structured-merge-diff v4 and v6 that may require updated dependencies or network connectivity during build.