feat(comments): hide every comment mention when COMMENTS_ENABLED=false

The kill-switch previously left comment UI/text visible in several places.
Sweep the whole surface so a comments-off instance shows no trace:

Frontend (main app):
- VirtualFeed grid tile: gate the comment button/count on $commentsEnabled
  (was ungated — the only feed surface still showing it).
- admin stats: hide the "Kommentare" count card.
- UploadSheet "Uploads geschlossen" notice, host ban-modal description, and
  host/admin unban confirmations: drop the "…und kommentieren" wording.
- export page: drop "Kommentaren" from the keepsake description.

Keepsake export (had no concept of the flag):
- export.rs: thread comments_enabled into the exported data (ViewerEvent),
  wired through spawn_export_jobs/recover_exports and their call sites
  (host.rs, main.rs).
- export-viewer: gate comment counts (list + grid) and the lightbox comments
  section; older exports without the field default to enabled (?? true).

Backend still 403s comment writes when disabled (unchanged) — this is the UI
half so stale clients and archives match.

Verified on the running stack (COMMENTS_ENABLED=false): /event reports
comments_enabled=false, a regenerated keepsake embeds "comments_enabled": false
with no comment UI, and the uploads-closed notice renders "…ansehen und liken."

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/handlers/host.rs

@@ -302,6 +302,7 @@ pub async fn rebuild_export(
         r.event_id,
         r.event_name,
         r.epoch,
+        state.config.comments_enabled,
         std::time::Duration::ZERO,
         state.pool.clone(),
         state.config.media_path.clone(),
@@ -549,6 +550,7 @@ pub fn start_regen(state: &AppState, regen: crate::services::export::PendingRege
         regen.event_id,
         regen.event_name,
         regen.epoch,
+        state.config.comments_enabled,
         // Debounced: a takedown pass is a burst, and each request retires the last generation. The
         // delay lets superseded workers fail their claim and do zero work instead of each building
         // a full archive. See export::REGEN_DEBOUNCE.
@@ -753,6 +755,7 @@ pub async fn release_gallery(
         event_id,
         event_name,
         epoch,
+        state.config.comments_enabled,
         std::time::Duration::ZERO,
         state.pool.clone(),
         state.config.media_path.clone(),

backend/src/main.rs

@@ -58,6 +58,7 @@ async fn main() -> Result<()> {
         pool.clone(),
         config.media_path.clone(),
         config.export_path.clone(),
+        config.comments_enabled,
         state.sse_tx.clone(),
     )
     .await;

backend/src/services/export.rs

@@ -53,6 +53,9 @@ struct ViewerData {
 struct ViewerEvent {
     name: String,
     exported_at: String,
+    // Mirrors the live COMMENTS_ENABLED flag so the offline keepsake hides all comment
+    // UI (buttons, counts, sections) when the feature was off for the event.
+    comments_enabled: bool,
 }
 
 #[derive(Serialize)]
@@ -238,6 +241,7 @@ pub async fn recover_exports(
     pool: PgPool,
     media_path: PathBuf,
     export_path: PathBuf,
+    comments_enabled: bool,
     sse_tx: broadcast::Sender<SseEvent>,
 ) {
     let rows = match sqlx::query_as::<_, (Uuid, String, i64)>(
@@ -297,6 +301,7 @@ pub async fn recover_exports(
             event_id,
             event_name,
             epoch,
+            comments_enabled,
             Duration::ZERO,
             pool.clone(),
             media_path.clone(),
@@ -403,6 +408,7 @@ pub fn spawn_export_jobs(
     event_id: Uuid,
     event_name: String,
     epoch: i64,
+    comments_enabled: bool,
     delay: Duration,
     pool: PgPool,
     media_path: PathBuf,
@@ -439,6 +445,7 @@ pub fn spawn_export_jobs(
             event_id,
             epoch,
             &event_name2,
+            comments_enabled,
             &pool2,
             &media_path2,
             &export_path2,
@@ -635,10 +642,12 @@ impl MediaSource {
     }
 }
 
+#[allow(clippy::too_many_arguments)]
 async fn run_html_export(
     event_id: Uuid,
     epoch: i64,
     event_name: &str,
+    comments_enabled: bool,
     pool: &PgPool,
     media_path: &Path,
     export_path: &Path,
@@ -653,6 +662,7 @@ async fn run_html_export(
         epoch,
         event_id,
         event_name,
+        comments_enabled,
         pool,
         media_path,
         export_path,
@@ -672,10 +682,12 @@ async fn run_html_export(
     abandon_if_superseded("HTML", event_id, epoch, res)
 }
 
+#[allow(clippy::too_many_arguments)]
 async fn run_html_export_inner(
     epoch: i64,
     event_id: Uuid,
     event_name: &str,
+    comments_enabled: bool,
     pool: &PgPool,
     media_path: &Path,
     export_path: &Path,
@@ -882,6 +894,7 @@ async fn run_html_export_inner(
         event: ViewerEvent {
             name: event_name.to_string(),
             exported_at: Utc::now().to_rfc3339(),
+            comments_enabled,
         },
         posts: viewer_posts,
     };