Implement Official Keycloak JS Adapter with Proxy-Aware Configuration

MAJOR ENHANCEMENT: Complete Keycloak integration with proper HTTPS/proxy handling

## Core Improvements:

### 1. Enhanced Configuration (nuxt.config.ts)
- Added proxy trust configuration for nginx environments
- Configured baseUrl for production HTTPS enforcement
- Added debug mode configuration for development

### 2. Proxy-Aware Keycloak Composable (composables/useKeycloak.ts)
- Intelligent base URL detection (production vs development)
- Force HTTPS redirect URIs in production environments
- Enhanced debugging and logging capabilities
- Proper PKCE implementation for security
- Automatic token refresh mechanism

### 3. Dual Authentication System
- Updated middleware to support both Directus and Keycloak
- Enhanced useUnifiedAuth for seamless auth source switching
- Maintains backward compatibility with existing Directus users

### 4. OAuth Flow Implementation
- Created proper callback handler (pages/auth/callback.vue)
- Comprehensive error handling and user feedback
- Automatic redirect to dashboard on success

### 5. Enhanced Login Experience (pages/login.vue)
- Restored SSO login button with proper error handling
- Maintained existing Directus login form
- Clear separation between auth methods with visual divider

### 6. Comprehensive Testing Suite (pages/dashboard/keycloak-test.vue)
- Real-time configuration display
- Authentication status monitoring
- Interactive testing tools
- Detailed debug logging system

## Technical Solutions:

 **Proxy Detection**: Automatically detects nginx proxy and uses correct HTTPS URLs
 **HTTPS Enforcement**: Forces secure redirect URIs in production
 **Error Handling**: Comprehensive error catching with user-friendly messages
 **Debug Capabilities**: Enhanced logging for troubleshooting
 **Security**: Implements PKCE and secure token handling

## Infrastructure Compatibility:
- Works with nginx reverse proxy setups
- Compatible with Docker container networking
- Handles SSL termination at proxy level
- Supports both development and production environments

This implementation specifically addresses the HTTP/HTTPS redirect URI mismatch
that was causing 'unauthorized_client' errors in the proxy environment.

pages/auth/callback.vue

@@ -0,0 +1,79 @@
+<template>
+  <v-app>
+    <v-main>
+      <v-container class="fill-height" fluid>
+        <v-row align="center" justify="center" class="fill-height">
+          <v-col cols="12" class="text-center">
+            <v-progress-circular 
+              :size="70" 
+              :width="7" 
+              color="primary" 
+              indeterminate
+            ></v-progress-circular>
+            <h3 class="mt-4">Processing authentication...</h3>
+            <p class="text-body-2 mt-2">Please wait while we complete your login</p>
+          </v-col>
+        </v-row>
+      </v-container>
+    </v-main>
+  </v-app>
+</template>
+
+<script setup lang="ts">
+// Define page meta for public access (no auth required)
+definePageMeta({
+  auth: false,
+  layout: false
+});
+
+// Handle OAuth callback
+onMounted(async () => {
+  try {
+    const route = useRoute()
+    const keycloak = useKeycloak()
+    
+    // Check if we have an authorization code
+    const code = route.query.code as string
+    const state = route.query.state as string
+    const error = route.query.error as string
+    
+    if (error) {
+      console.error('OAuth error:', error, route.query.error_description)
+      throw new Error(`Authentication failed: ${error}`)
+    }
+    
+    if (!code) {
+      throw new Error('No authorization code received')
+    }
+    
+    console.log('[CALLBACK] Processing OAuth callback with code:', code.substring(0, 10) + '...')
+    
+    // Initialize Keycloak if not already done
+    if (!keycloak.isInitialized.value) {
+      await keycloak.initKeycloak()
+    }
+    
+    // Check if user is now authenticated
+    if (keycloak.isAuthenticated.value) {
+      console.log('[CALLBACK] User authenticated successfully')
+      // Redirect to dashboard
+      await navigateTo('/dashboard')
+    } else {
+      throw new Error('Authentication process failed')
+    }
+    
+  } catch (error) {
+    console.error('[CALLBACK] Authentication error:', error)
+    
+    // Show error and redirect to login
+    const toast = useToast()
+    toast.error('Authentication failed. Unable to complete login. Please try again.')
+    
+    await navigateTo('/login')
+  }
+})
+
+useHead({
+  title: 'Authenticating...'
+})
+</script>