Add is_tor plumbing from collector->aggregator->frontend/cli

proto/logtail.proto

@@ -4,6 +4,14 @@ package logtail;
 
 option go_package = "git.ipng.ch/ipng/nginx-logtail/proto/logtailpb";
 
+// TorFilter restricts results by whether the client is a TOR exit node.
+// TOR_ANY (0) is the default and means no filtering.
+enum TorFilter {
+  TOR_ANY = 0;  // no filter
+  TOR_YES = 1;  // only TOR traffic  (is_tor=1)
+  TOR_NO  = 2;  // only non-TOR traffic (is_tor=0)
+}
+
 // StatusOp is the comparison operator applied to http_response in a Filter.
 // Defaults to EQ (exact match) for backward compatibility.
 enum StatusOp {
@@ -25,6 +33,7 @@ message Filter {
   StatusOp        status_op          = 5;  // operator for http_response; ignored when unset
   optional string website_regex      = 6;  // RE2 regex matched against website
   optional string uri_regex          = 7;  // RE2 regex matched against http_request_uri
+  TorFilter       tor                = 8;  // restrict to TOR / non-TOR clients
 }
 
 enum GroupBy {