Add post video upload (#22)

Questions and replies can attach one MP4 or WebM (25 MB) alongside up to four images. Videos are stored as-is and omitted from Discord embeds.

Reviewed-on: #22
Co-authored-by: codegirl-007 <s.raide@gmail.com>

internal/web/events_test.go

@@ -236,3 +236,21 @@ func assertPostEvent(t *testing.T, got, want events.PostEvent) {
 		t.Fatalf("event = %+v, want %+v", got, want)
 	}
 }
+
+func TestPostEventOmitsVideos(t *testing.T) {
+	t.Parallel()
+
+	srv, _ := newTestServer(t, Config{})
+	got := srv.postEvent(&store.Post{
+		ID:     "root-1",
+		Title:  "Clip",
+		Body:   "Photo and video.",
+		Images: []store.PostImage{
+			{PublicURL: "https://cdn.example/a.jpg", Description: "Still", Kind: store.MediaKindImage},
+			{PublicURL: "https://cdn.example/a.mp4", Description: "Walkthrough", Kind: store.MediaKindVideo},
+		},
+	}, nil, nil)
+	if len(got.Images) != 1 || got.Images[0].URL != "https://cdn.example/a.jpg" {
+		t.Fatalf("event images = %+v", got.Images)
+	}
+}