Fix: Wrap tool results in TextContent format for MCP protocol compliance

The MCP protocol requires tool call results to be wrapped in content items
with type and text fields. This matches what other MCP servers do.

Before: {"result": [{"name": "testdb", ...}]}
After:  {"result": [{"type": "text", "text": "[{\"name\": \"testdb\", ...}]"}]}

This should fix the issue where Claude Code was timing out waiting for responses.

scripts/mcp/proxysql_mcp_stdio_bridge.py

@@ -471,17 +471,22 @@ class StdioMCPServer:
             debug_log(f"[tools/call] Unwrapped result:")
             debug_log(f"    {json.dumps(actual_result, indent=4)}")
             log_separator("-")
+            # Wrap in TextContent for MCP protocol compliance
+            wrapped_result = [{"type": "text", "text": json.dumps(actual_result, indent=2)}]
+            debug_log(f"[tools/call] Wrapped in TextContent: {json.dumps(wrapped_result, indent=4)}")
             return {
                 "jsonrpc": "2.0",
-                "result": actual_result,
+                "result": wrapped_result,
                 "id": req_id
             }
 
-        # Fallback: return result as-is
-        debug_log(f"[tools/call] No wrapping detected, returning result as-is")
+        # Fallback: return result as-is, wrapped in TextContent
+        debug_log(f"[tools/call] No wrapping detected, wrapping result in TextContent")
+        wrapped_result = [{"type": "text", "text": json.dumps(proxysql_result, indent=2)}]
+        debug_log(f"[tools/call] Wrapped result: {json.dumps(wrapped_result, indent=4)}")
         return {
             "jsonrpc": "2.0",
-            "result": proxysql_result,
+            "result": wrapped_result,
             "id": req_id
         }