gosec govulncheck runs (#1)

* gosec govulncheck runs

* Fix flaky TestRateLimiter_Matrix test

The test was failing due to two issues:
1. Test name generation used invalid character conversion (string(rune('0'+limit)))
   which produced non-printable characters for limits >= 10
2. Using 10ms windows with 100 requests caused race conditions - early requests
   would expire before all 100 were made, allowing the 101st request

Changed to use struct-based test cases with proper fmt.Sprintf naming and
a consistent 1-second window that won't expire during rapid test execution.

internal/client/client.go

@@ -44,7 +44,7 @@ func (c *Client) Connect() error {
 
 	// Close existing connection if any
 	if c.conn != nil {
-		c.conn.Close()
+		_ = c.conn.Close()
 		c.conn = nil
 		c.reader = nil
 	}
@@ -83,7 +83,7 @@ func (c *Client) send(req *protocol.Request) (*protocol.Response, error) {
 	}
 
 	// Set deadline
-	c.conn.SetDeadline(time.Now().Add(c.timeout))
+	_ = c.conn.SetDeadline(time.Now().Add(c.timeout))
 
 	// Send request
 	data, err := json.Marshal(req)