fix(relays): the generic HTTP board never sent its URLs; cluster filters start off

buildDeviceDriver had no case for "httpgen", so the generic board fell through
to the WebSwitch driver: it polled an address it had never been given, reported
itself offline, greyed out every relay button, and sent none of the configured
URLs. Nothing in the interface said so — the board was configured, saved and
listed, and simply did nothing. deviceKey did not cover the URLs either, so once
that is fixed, correcting a typo in one would still have handed back the cached
driver holding the old address until a restart.

Two shapes of home-made switch could not be described at all:

  - a bit-mask board whose four URLs differ by one character
    (/Set0/1, /Set0/2, /Set0/4, /Set0/8) — {value} in the pattern now takes the
    number from the per-relay box, keeping the address in one place;
  - a board numbering its channels from zero — {relay-1}, since giving up the
    pattern for eight hand-typed URLs was the only alternative.

The pattern decides what the per-relay boxes hold, and the grid says which as
soon as {value} is typed: guessing per box ("does this look like a URL?") would
change meaning on a typo, which is not a thing to do to something wired to an
antenna. A URL typed without a scheme gets http:// like the named boards get
from relayBase; https:// is passed through untouched.

Host and the connection test are gone for this type. It has no address of its
own — its relays may each live on a different box — and no status to read, so a
test could only ever answer "OK, 4 relays". Save was greyed out without a host,
which made a complete configuration of four full URLs impossible to store.

Cluster filters no longer persist across launches. A band lock set weeks earlier
is invisible to whoever set it: the counter reads 76 spots live, the grid is
empty, and the search goes to the cluster instead. Nobody loses work by
re-ticking a chip. Grouping and the panel state still persist — they change how
spots look, never whether they appear.

relayhttpgen_test.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+// The generic HTTP board must actually be built from its URLs.
+//
+// It was not: buildDeviceDriver had no case for it, so it fell through to the
+// WebSwitch driver. The board was configured, saved, listed — and every command
+// went to a WebSwitch address that did not exist, which also left the device
+// reported as offline and every relay button on the panel greyed out. Nothing in
+// the UI said so; the URLs were simply never sent.
+func TestGenericHTTPBoardSendsItsConfiguredURL(t *testing.T) {
+	hit := make(chan string, 4)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		hit <- r.URL.Path
+	}))
+	defer srv.Close()
+
+	// Host deliberately empty — this board's whole address is in the URLs.
+	d := StationDevice{
+		Type:     "httpgen",
+		Channels: 2,
+		OnURLs:   []string{srv.URL + "/relay1/on", srv.URL + "/relay2/on"},
+		OffURLs:  []string{srv.URL + "/relay1/off", srv.URL + "/relay2/off"},
+	}
+	if err := buildDeviceDriver(d).Set(context.Background(), 2, true); err != nil {
+		t.Fatalf("Set: %v", err)
+	}
+	select {
+	case got := <-hit:
+		if got != "/relay2/on" {
+			t.Errorf("board was asked for %q, want /relay2/on", got)
+		}
+	case <-time.After(3 * time.Second):
+		t.Fatal("the configured URL was never requested — the board is not using its own driver")
+	}
+}
+
+// Editing a URL must rebuild the driver. The cached one is keyed by the device's
+// configuration, and the URLs used not to be part of that key: correcting a typo
+// handed back the driver still holding the old address, so the fix looked like it
+// had done nothing until OpsLog was restarted.
+func TestGenericHTTPBoardKeyCoversItsURLs(t *testing.T) {
+	a := StationDevice{Type: "httpgen", Channels: 2, OnURLs: []string{"http://box/a"}}
+	b := StationDevice{Type: "httpgen", Channels: 2, OnURLs: []string{"http://box/b"}}
+	if deviceKey(a) == deviceKey(b) {
+		t.Error("two boards with different URLs share a cache key — an edited URL would not take effect")
+	}
+	c := a
+	c.OnPat = "http://box/{relay}"
+	if deviceKey(a) == deviceKey(c) {
+		t.Error("changing the ON pattern left the cache key unchanged")
+	}
+}