Connections, "every packet" rules, and a packet tracer

- Connections: the kernel's tracked connections, read and closed over
  ctnetlink (internal/conntrack, raw netlink like the drop log), with
  their NAT and TCP state; closing one makes the rules check its next
  packet again (GET /connections, POST /connections/close; hc
  connections; Traffic → Connections).
- Rules can check every packet (every_packet, --every-packet): before
  established connections are accepted, so a drop or reject also stops
  connections already open. They can't accept.
- A packet tracer (internal/trace): a table of its own, inet
  housecarl-trace, marks the packets a filter picks, `nft monitor trace`
  reports every rule and policy they meet in every table, and the tracer
  names what accepted or dropped them, Housecarl's rules by name (POST,
  GET, DELETE /trace; hc trace; Traffic → Trace). One trace at a time,
  at most 200 packets and 20 a second; the table goes when it ends.

e2e: 157 checks, among them an upload a normal block doesn't stop and an
every-packet one does, and a trace naming the blocking rule.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/routes_cfg.go

@@ -1,6 +1,10 @@
 package server
 
-import "encoding/json"
+import (
+	"encoding/json"
+
+	"housecarl/internal/trace"
+)
 
 // otherTables lists the tables in an `nft -j list ruleset` other than
 // Housecarl's ("inet main").
@@ -18,7 +22,7 @@ func otherTables(data []byte) []string {
 			continue
 		}
 		var t struct{ Family, Name string }
-		if json.Unmarshal(raw, &t) == nil && !(t.Family == "inet" && t.Name == "housecarl") {
+		if json.Unmarshal(raw, &t) == nil && !(t.Family == "inet" && (t.Name == "housecarl" || t.Name == trace.Table)) {
 			out = append(out, t.Family+" "+t.Name)
 		}
 	}