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/target_http.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	"sort"
 	"sync"
 	"time"
@@ -32,6 +33,11 @@ type HTTPTargetConfig struct {
 	URL     string            `json:"url"`
 	Headers map[string]string `json:"headers,omitempty"`
 	Timeout int               `json:"timeout,omitempty"`
+
+	// ForwardQuery passes each event's query string on to the target,
+	// appended to URL. Off, the target URL is sent exactly as
+	// configured.
+	ForwardQuery bool `json:"forwardQuery,omitempty"`
 }
 
 // httpCore holds the retry, backoff, and circuit-breaker
@@ -444,6 +450,10 @@ func (t *httpTarget) doHTTPRequest(
 		)
 	}
 
+	if cfg.ForwardQuery {
+		appendQuery(req.URL, event.RawQuery)
+	}
+
 	originScoped := applyRequestHeaders(
 		req, event, cfg, t.eng.userAgent(),
 	)
@@ -474,6 +484,19 @@ func (t *httpTarget) doHTTPRequest(
 	return resp.StatusCode, string(body), dur, nil
 }
 
+// appendQuery adds an event's query string to a delivery's URL, joined
+// with "&" to any query string the target URL already has.
+func appendQuery(u *url.URL, rawQuery string) {
+	switch {
+	case rawQuery == "":
+		return
+	case u.RawQuery == "":
+		u.RawQuery = rawQuery
+	default:
+		u.RawQuery += "&" + rawQuery
+	}
+}
+
 // clientForRequest returns the client for one delivery attempt.
 // originScoped is the header set applyRequestHeaders built for that
 // attempt; a request with neither a per-target timeout nor an