Actually use a zero width space to prevent timestamps being detected as events.

Zero-width space (200b) is deprecated, but the new way (word joiner - 2060)
doesn't work yet (at least not in Chrome/Mac since it switched to HarfBuzz)

app/digest.go

@@ -42,7 +42,7 @@ func safeFormattedDate(date string) string {
 		} else {
 			buffer.WriteString(date[i : i+2])
 		}
-		buffer.WriteString("\u2060")
+		buffer.WriteString("\u200b")
 	}
 	return buffer.String()
 }