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

templates/source_detail.html

@@ -135,6 +135,7 @@
              data-destination="{{.TargetForm.URL}}"
              data-headers="{{.TargetForm.Headers}}"
              data-timeout="{{.TargetForm.Timeout}}"
+             {{if .TargetForm.ForwardQuery}}data-forward-query{{end}}
              data-max-retries="{{.TargetForm.MaxRetries}}"
              data-expiry="{{.TargetForm.Expiry}}"
              data-rotation="{{.TargetForm.Rotation}}">
@@ -183,6 +184,13 @@
                                 <label class="text-sm text-gray-700">Timeout (seconds, blank = default):</label>
                                 <input type="number" name="timeout" :value="timeout" min="0" max="300" class="input text-sm w-24">
                             </div>
+                            <div>
+                                <label class="flex items-center gap-2 text-sm text-gray-700">
+                                    <input type="checkbox" name="forward_query" value="on" :checked="forwardQuery" class="h-4 w-4">
+                                    Pass the query string on to this target
+                                </label>
+                                <p class="text-xs text-gray-500 mt-1">Appends the query string each event arrived with to the URL above, after any query string the URL already has.</p>
+                            </div>
                             <div>
                                 <div class="flex gap-2 items-center">
                                     <label class="text-sm text-gray-700">Delivery attempts:</label>