New feature:

Improved directsearch with streaming overview reading for better reliability and performance

Main changes

• Replaced directsearch batch overview processing with streaming line-by-line reading
• Added overviewReader() function that reads individual overview lines from NNTP server
• Decoupled reading lines from processing of matching lines for better concurrency
• Added OverviewTimeout configuration parameter (default: 5 seconds)
• Added OverviewRetries configuration parameter (default: 3 retries)
• Implemented timeout handling with automatic restart of failed overview readers
• Added recovery mechanism for partial failures via maybeRestartOverviewSearch()

Additional changes

• Added Debug() function to Logger struct for debug-level logging
• Debug messages only written to log file (not console) when debug mode enabled
• Added debug logging for connection pool status (every 5 seconds)
• Improved warning filtering (502 errors logged as debug instead of warnings)
• Updated Go version from 1.24.0 to 1.25.0
• Updated multiple dependencies (nntp, nntpPool, progressbar, etc.)
• Various transitive dependency updates