zap: hide the disabled zap button instead of showing a dead one

Root cause of "have to click the Zap button several times before it opens":
the button is intentionally hidden+disabled until the creator's Lightning
address resolves (~2s profile fetch), but .video-modal__action-button sets
display: inline-flex, which overrode the UA `[hidden] { display:none }`. So
the button rendered and looked clickable while still a disabled no-op, and
disabled buttons don't fire click events. Add
`.video-modal__action-button[hidden] { display:none }` so it only appears
once enabled/ready (restoring the intended "show zap only when zappable"
behaviour).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

css/tailwind.source.css

@@ -2590,6 +2590,14 @@
     border-style: solid;
   }
 
+  /* `display: inline-flex` above overrides the UA `[hidden] { display: none }`,
+     which left the zap button visible (and clickable-looking) while it was still
+     `hidden`+`disabled` during load — users clicked a dead button repeatedly. Make
+     the hidden attribute win so the button only appears once it's enabled/ready. */
+  .video-modal__action-button[hidden] {
+    display: none;
+  }
+
   .video-modal__action-label {
     @apply hidden sm:inline;
   }