You are given a base class Logger with a virtual function log() that prints a timestamp message.

Create a derived class FileLogger that:
- Publicly inherits from Logger
- Has a private string member: filename
- Has a constructor taking a string filename
- Overrides log() to:
  1. First call Logger::log() (to print the timestamp)
  2. Then print "Saving to: [filename]"

This pattern is common in real software: the derived class extends (not replaces) the base behavior.

Do NOT include a main function. Your code will be tested automatically.

Expected output:
[LOG] Timestamp recorded
Saving to: output.txt