log: add file rotation support based on size and time intervals

[Dominik-esb]

What this PR does / why we need it

This PR adds log rotation functionality to the windows_exporter logger to prevent log files from growing indefinitely and consuming excessive disk space.

The implementation adds a new rotate package that provides:

• Size-based rotation: Automatically rotates logs when a file exceeds a configurable size limit
• Time-based rotation: Automatically rotates logs at configurable time intervals (e.g., daily, hourly)
• Archive management: Automatically deletes old log files to maintain a configurable number of archived logs
• Thread-safe operations: Uses mutex locking to prevent corruption from concurrent writes

The FileWriter type implements the io.Writer interface, making it a drop-in replacement for standard file writers. Rotated files are renamed with timestamps (e.g., app-2026-01-08-1704672000.log) to ensure unique names and easy identification.

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

• fixes #

Special notes for your reviewer

• This PR only adds the rotation infrastructure (internal/log/rotate.go). Integration into the existing logger (internal/log/logger.go) will be needed.
• The implementation is inspired by the Telegraf log rotation.

Particularly user-facing changes

Once integrated into the logger, users will be able to configure:

• --log.rotation-interval: Time interval for log rotation (e.g., 24h for daily rotation, 0 to disable)
• --log.rotation-max-size: Maximum log file size in bytes before rotation (e.g., 10485760 for 10MB, 0 to disable)
• --log.rotation-max-archives: Number of archived log files to keep (-1 to keep all)

Example configuration:

log:
  file: /var/log/windows_exporter.log
  rotation-interval: 24h
  rotation-max-size: 104857600  # 100MB
  rotation-max-archives: 7      # Keep 7 days of logs

Checklist

Complete these before marking the PR as ready to review:

• DCO signed
• The PR title has a summary of the changes and the area they affect
• The PR body has a summary to reflect any significant (and particularly user-facing) changes introduced by this PR