feat: add admin operations documentation and scripts for server management (#323)

## Summary
- Added comprehensive admin operations documentation
- Included scripts for common server management tasks

Together with #315, #316, this fixes #182

tools/admin/auth.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+# Simple OIDC authentication helper using gcloud
+
+REGISTRY_URL="${REGISTRY_URL:-https://registry.modelcontextprotocol.io}"
+
+if ! gcloud projects list &> /dev/null; then
+    gcloud auth login >&2
+fi
+
+# Get Google Cloud identity token
+OIDC_TOKEN=$(gcloud auth print-identity-token)
+
+# Exchange for registry token
+RESPONSE=$(curl -s -X POST "${REGISTRY_URL}/v0/auth/oidc" \
+  -H "Content-Type: application/json" \
+  -d "{\"oidc_token\": \"${OIDC_TOKEN}\"}")
+
+# Check if successful
+REGISTRY_TOKEN=$(echo "$RESPONSE" | jq -r '.registry_token // empty')
+
+if [ -z "$REGISTRY_TOKEN" ]; then
+    echo "Error: Authentication failed" >&2
+    echo "$RESPONSE" | jq '.' >&2
+    exit 1
+fi
+
+# Output the export command
+echo "# Successfully authenticated! Now run this to use your token:" >&2
+echo "export REGISTRY_TOKEN='${REGISTRY_TOKEN}'"