fix: redirect MCP server logs to stderr to preserve JSON-RPC protocol

MCP uses stdio transport where stdout is reserved for JSON-RPC messages.
Console.log was writing startup logs to stdout, causing Claude Desktop
to parse "[2025-12-19..." as a JSON array and fail.

Fixes #396

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugin/.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "claude-mem",
-  "version": "7.4.0",
+  "version": "7.4.1",
   "description": "Persistent memory system for Claude Code - seamlessly preserve context across sessions",
   "author": {
     "name": "Alex Newman"