refactor: rename search-server to mcp-server throughout codebase

- Updated all documentation references from search-server to mcp-server
- Removed legacy search-server.cjs file
- Updated debug log messages to use [mcp-server] prefix
- Updated build output references in docs

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

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

docs/public/configuration.mdx

@@ -82,7 +82,7 @@ ${CLAUDE_PLUGIN_ROOT}/
 │   ├── summary-hook.js     # Summary generation hook
 │   ├── cleanup-hook.js     # Session cleanup hook
 │   ├── worker-service.cjs  # Worker service (CJS)
-│   └── search-server.cjs   # MCP search server (CJS)
+│   └── mcp-server.cjs      # MCP search server (CJS)
 └── ui/
     └── viewer.html         # Web viewer UI bundle
 ```