Bulk delete, editable share links, gallery filter fix

- shift-click selects ranges in the gallery; selection bar gains
  'Delete N' with a single confirm (POST /api/photos/delete)
- PATCH /api/shares/{id}: allow_download and expiry editable in place,
  token and client feedback preserved
- Gallery: re-attach ResizeObserver via callback ref — after a filter
  with zero matches the gallery stayed blank at width 0

src/routes/shares.rs

@@ -138,6 +138,49 @@ pub async fn create(
     Ok(Json(share_json(&state, &row)))
 }
 
+/// Distinguishes an absent JSON field (keep current value) from an explicit
+/// null (clear the expiry): absent → None, present → Some(inner).
+fn double_option<'de, D>(de: D) -> Result<Option<Option<DateTime<Utc>>>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    serde::Deserialize::deserialize(de).map(Some)
+}
+
+#[derive(Deserialize)]
+pub struct UpdateShare {
+    allow_download: Option<bool>,
+    #[serde(default, deserialize_with = "double_option")]
+    expires_at: Option<Option<DateTime<Utc>>>,
+}
+
+pub async fn update(
+    State(state): State<AppState>,
+    Path(share_id): Path<Uuid>,
+    Json(body): Json<UpdateShare>,
+) -> ApiResult<Json<serde_json::Value>> {
+    let updated = sqlx::query(
+        "update shares set
+             allow_download = coalesce($2, allow_download),
+             expires_at = case when $3 then $4 else expires_at end
+         where id = $1",
+    )
+    .bind(share_id)
+    .bind(body.allow_download)
+    .bind(body.expires_at.is_some())
+    .bind(body.expires_at.flatten())
+    .execute(&state.db)
+    .await?;
+    if updated.rows_affected() == 0 {
+        return Err(ApiError::not_found());
+    }
+    let row: ShareAdminRow = sqlx::query_as(&format!("{SHARE_SELECT} where s.id = $1"))
+        .bind(share_id)
+        .fetch_one(&state.db)
+        .await?;
+    Ok(Json(share_json(&state, &row)))
+}
+
 /// Clear a share's password-lockout state (e.g. after a client fat-fingered
 /// their way into the 15-minute lock).
 pub async fn reset_lock(