Store and show an event's query string, and pass it on to an HTTP target when set (closes #312)

The receiver dropped the query string of every request it received, so a sender's URL parameters were silently lost. Each event now keeps it, as sent, in a new `raw_query` column of the per-webhook `events` table; a resubmitted copy carries its original's. The event log and the event's page show it in the shared request block, the event log leaving out one over 32 KiB with a link, as for headers. The archive and log targets carry it. HTTP targets gain "Pass the query string on to this target", off by default: on, deliveries, replays and resubmits append it to the target URL, joined with `&` to one already there. The access log still hides it.

Model: opus-5-5

internal/delivery/engine_test.go

@@ -11,6 +11,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -1990,6 +1991,10 @@ func assertLogLineComplete(
 		"log line must contain the full request headers",
 	)
 
+	assert.Contains(t, out, "raw_query="+strconv.Quote(event.RawQuery),
+		"log line must contain the query string",
+	)
+
 	assert.Contains(t, out, event.EntrypointID,
 		"log line must contain the entrypoint id",
 	)
@@ -2012,6 +2017,7 @@ func TestDeliverLog_LogsFullContent(t *testing.T) {
 	event := seedEvent(
 		t, db, `{"log-body-marker":"abc123"}`,
 	)
+	event.RawQuery = eventQuery
 
 	dlv := seedDelivery(
 		t, db, event.ID, uuid.New().String(),