feat(server): Experimental support for OAuth2/OIDC authentication

env.sample

@@ -1,3 +1,23 @@
+# Nextcloud Instance
 NEXTCLOUD_HOST=
+
+# ===== AUTHENTICATION MODE =====
+# Choose ONE of the following:
+
+# Option 1: OAuth2/OIDC (RECOMMENDED - More Secure)
+# - Requires Nextcloud OIDC app installed and configured
+# - Admin must enable "Dynamic Client Registration" in OIDC app settings
+# - Leave NEXTCLOUD_USERNAME and NEXTCLOUD_PASSWORD empty to use OAuth mode
+# - Optional: Pre-register client and provide credentials (otherwise auto-registers)
+NEXTCLOUD_OIDC_CLIENT_ID=
+NEXTCLOUD_OIDC_CLIENT_SECRET=
+NEXTCLOUD_OIDC_CLIENT_STORAGE=.nextcloud_oauth_client.json
+NEXTCLOUD_MCP_SERVER_URL=http://localhost:8000
+
+# Option 2: Basic Authentication (LEGACY - Less Secure)
+# - Requires username and password
+# - Credentials stored in environment variables
+# - Use only for backward compatibility or if OAuth unavailable
+# - If these are set, OAuth mode is disabled
 NEXTCLOUD_USERNAME=
 NEXTCLOUD_PASSWORD=