feat: standardize mcp server names (#30)

Author: averikitsch

gemini-extension.json

@@ -3,7 +3,7 @@
   "version": "0.1.0",
   "description": "Connect and interact with Spanner data using natural language.",
   "mcpServers": {
-    "Spanner": {
+    "spanner": {
       "command": "${extensionPath}${/}toolbox",
       "args": [
         "--prebuilt",