Fix Photos Add, Remove, and Replace against the library picker.

Remove clears the Photos array and backing image fields; Add opens the picker with disk upload and drops empty drafts on cancel.

Co-authored-by: Cursor <cursoragent@cursor.com>

components/studio2/AssetSlot.vue

@@ -4,12 +4,14 @@
    type="button"
    class="slot-thumb"
    :class="asset ? 'slot-thumb--slot' : 'slot-thumb--empty'"
-   :aria-label="asset ? 'Replace photo' : 'Select photo'"
+   :aria-label="asset ? 'Replace photo' : 'Choose a photo'"
    @click="$emit('pick')"
   >
    <span v-if="asset && hidden" class="p-2 text-center text-[var(--type-sm)] text-[var(--muted)]">Still loaded · preview hidden</span>
    <img v-else-if="asset" :src="thumbSrc" alt="">
-   <span v-else class="inline-flex items-center gap-1">Select <span aria-hidden="true">▾</span></span>
+   <span v-else class="inline-flex flex-col items-center gap-1 px-2 text-center">
+    <span>Choose a photo</span>
+   </span>
   </button>
   <div class="photo-card-body">
    <label class="photo-role-label">
@@ -31,6 +33,11 @@
      title="Mention this photo in the prompt"
      @click.stop="$emit('mention')"
     >Mention in prompt</button>
+    <button
+     v-if="!readonly && asset"
+     type="button"
+     @click.stop="$emit('pick')"
+    >Replace</button>
     <button v-if="!readonly" type="button" @click.stop="$emit('remove')">Remove</button>
    </div>
   </div>