[New] Document scan_progress_log_interval in conf.maldet, man page, allowlist

[New] conf.maldet: scan_progress_log_interval in SCAN PROGRESS LOGGING section
[New] maldet.1: detailed description and summary listing
[Change] _safe_source_conf: add scan_progress_log_interval to allowlist

Author: rfxn

files/conf.maldet

@@ -508,3 +508,13 @@ session_legacy_compat="auto"
 # [ string length in characters, default = 150000 ]
 string_length_scan="0"		# [ 0 = disabled, 1 = enabled ]
 string_length="150000"		# [ max string length ]
+
+##
+# [ SCAN PROGRESS LOGGING ]
+##
+# Interval in seconds between progress checkpoints written to the
+# event log during background scans (maldet -b). Each checkpoint
+# reports the current scan stage, files processed, percentage,
+# elapsed time, and estimated time remaining.
+# [ 0 = disabled, default = 60 ]
+scan_progress_log_interval="60"

files/internals/lmd_config.sh

@@ -251,6 +251,7 @@ _build_co_allowed_pattern() {
 	_pat="${_pat}|enable_statistic|elk_host|elk_port|elk_index"
 	_pat="${_pat}|string_length_scan|string_length"
 	_pat="${_pat}|session_legacy_compat"
+	_pat="${_pat}|scan_progress_log_interval"
 	_pat="${_pat})\$"
 	printf -v "$1" '%s' "$_pat"
 }

files/maldet.1

@@ -322,7 +322,8 @@ Key variables by category:
 .BR scan_ignore_user ,
 .BR scan_ignore_group ,
 .BR string_length_scan ,
-.BR string_length .
+.BR string_length ,
+.BR scan_progress_log_interval .
 .PP
 .B Quarantine:
 .BR quarantine_hits ,
@@ -458,6 +459,15 @@ A value of 0 disables the timeout.
 Values between 1 and 59 are silently ignored (minimum is 60).
 Default: 0.
 .PP
+.B scan_progress_log_interval
+sets the interval in seconds between progress checkpoints written to the
+event log during background scans
+.RB ( "maldet \-b" ).
+Each checkpoint reports the current scan stage, files processed, percentage
+complete, elapsed time, and estimated time remaining.
+A value of 0 disables progress logging.
+Default: 60.
+.PP
 .B scan_days
 sets the number of days to look back for recently modified files during
 daily cron scans.