style(clippy): auto-fix code style issues and unnecessary map_or allocations detected by cargo clippy

server/src/handlers/workspaces.rs

@@ -275,7 +275,7 @@ impl McpTool for ListContextWorkspacesHandler {
         let data = state.context_workspaces.read_with(|ws| {
             let filtered: Vec<_> = ws
                 .iter()
-                .filter(|w| req.namespace.as_ref().map_or(true, |ns| &w.namespace == ns))
+                .filter(|w| req.namespace.as_ref().is_none_or(|ns| &w.namespace == ns))
                 .collect();
             serde_json::to_string(&filtered).map_err(|e| e.to_string())
         })?;