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/target_edit.html

@@ -47,6 +47,14 @@
                 <input type="number" id="timeout" name="timeout" value="{{.TargetForm.Timeout}}" min="0" max="{{.MaxTimeout}}" class="input">
                 <p class="text-xs text-gray-500 mt-1">Per-request timeout, at most {{.MaxTimeout}} seconds. Leave blank to use the default.</p>
             </div>
+
+            <div class="form-group">
+                <label class="flex items-center gap-2 text-sm font-medium text-gray-700">
+                    <input type="checkbox" id="forward_query" name="forward_query" value="on"{{if .TargetForm.ForwardQuery}} checked{{end}} 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 destination URL, after any query string the URL already has.</p>
+            </div>
             {{end}}
 
             {{if eq .Target.Type "slack"}}