Add broker info box and human-readable time format support

[digiserg]

• Add info box to right side of broker list showing:

  • Total brokers and online/offline status
  • Active controller node
  • Partition and replica statistics with ISR data
  • Under-replicated and offline partition warnings

• Add support for human-readable time formats in topic configs:

  • Users can enter values like '1h', '1d', '7d', '1w'
  • Automatically converts to milliseconds for Kafka
  • Shows helpful tip when editing time-based configs
  • Applies to retention.ms, segment.ms, and other time configs

• Add GetClusterStats() method to fetch real-time ISR statistics

• Fix formatting to show labels and values on same line

• Add comprehensive tests for time parsing functionality

• Maintain 0 linting issues throughout