feat: live-host probe and sarif/markdown report export

adds an httpx-style -probe scanner reporting liveness, final status, page
title, server header and the redirect chain, plus -sarif/-markdown export
flags that serialize the collected run after the scan loop. the report
serializers live in a decoupled internal/report package consuming a raw-json
result model so they never import scan types.

man/sif.1

@@ -131,6 +131,9 @@ max crawl recursion depth (default 2).
 .B \-passive
 passive subdomain and historical url discovery from third\-party feeds (zero traffic to the target).
 .TP
+.B \-probe
+live\-host probe; reports liveness, final status, page title, server header and the redirect chain.
+.TP
 .B \-noscan
 skip the base url scan (robots.txt, etc).
 .SH OPTIONS
@@ -162,6 +165,12 @@ cookie header to send with every request.
 .BR \-rate\-limit " \fIn\fR"
 cap outbound requests per second (0 = unlimited, default 0).
 .TP
+.BR \-sarif " \fIfile\fR"
+write a sarif 2.1.0 report of the run to \fIfile\fR.
+.TP
+.BR \-md ", " \-\-markdown " \fIfile\fR"
+write a markdown report of the run to \fIfile\fR.
+.TP
 .B \-api
 emit json results and suppress the interactive output.
 .SH MODULES