feat: Add Azure external auth provider

.env.azure.example

@@ -0,0 +1,24 @@
+# Microsoft Entra (Azure AD) OAuth Configuration for Self-Hosted Supabase
+# Copy this file to your actual environment configuration and fill in the values
+
+# Azure Application (Client) ID
+# Get this from Azure Portal > App registrations > Your app > Overview
+AZURE_CLIENT_ID=your-application-client-id-here
+
+# Azure Client Secret
+# Get this from Azure Portal > App registrations > Your app > Certificates & secrets
+AZURE_CLIENT_SECRET=your-client-secret-value-here
+
+# Azure Tenant ID or 'common'
+# Options:
+#   - 'common': Multi-tenant (any Azure AD organization)
+#   - 'organizations': Any Azure AD organization (excludes personal accounts)
+#   - 'consumers': Personal Microsoft accounts only
+#   - Your specific tenant ID: Single-tenant (e.g., '12345678-1234-1234-1234-123456789012')
+# Get tenant ID from Azure Portal > App registrations > Your app > Overview
+AZURE_TENANT_ID=common
+
+# Notes:
+# 1. These variables are used in supabase/config.toml via env() substitution
+# 2. Never commit this file with real secrets to git
+# 3. After setting these, restart your Supabase services: docker-compose restart