feat(server,frontend): expose children endpoint + expand UI for container entries

server:
- add GET /api/archives/:id/entries/:uid/children → list_entry_children,
  calling list_child_entries with caller_bits so visibility model is enforced
- fix capture_handler: use result.status ("completed"/"failed") to set job
  status rather than always "completed", mirroring rearchive_handler; this
  surfaces partial playlist failures to the polling client

frontend:
- api.js: add fetchEntryChildren(archiveId, entryUid)
- EntryRow: one outer div.entry-row-outer (display:block) keeps nth-child
  striping correct; inner div.entry-row-main is the flex row with all column
  cells and event handling; .child-entries sits below inside the outer wrapper
- expand chevron appears when entry.child_count > 0; clicking fetches children
  lazily and renders ChildRow components reusing .col-* flex widths
- child-count badge shown next to title on container entries
- styles.css: scoped CSS with #entries-body > .entry-row-outer selectors
  (higher specificity than > div) to override flex on outer wrapper; inner row
  and column rules replicated at correct depth; nth-child, is-selected,
  is-multi-selected, url-cell hover all handled

crates/archivr-server/src/routes.rs

@@ -241,6 +241,10 @@ pub fn app_with_state(state: AppState) -> Router {
                 .patch(patch_entry_handler)
                 .delete(delete_entry_handler),
         )
+        .route(
+            "/api/archives/:archive_id/entries/:entry_uid/children",
+            get(list_entry_children),
+        )
         .route(
             "/api/archives/:archive_id/entries/:entry_uid/artifacts/:artifact_index",
             get(serve_artifact),
@@ -404,6 +408,18 @@ async fn list_entries(
     Ok(Json(archive::list_root_entries(&conn, caller_bits)?))
 }
 
+async fn list_entry_children(
+    State(state): State<AppState>,
+    auth: AuthUser,
+    Path((archive_id, entry_uid)): Path<(String, String)>,
+) -> Result<Json<Vec<archive::EntrySummary>>, ApiError> {
+    auth.require_auth()?;
+    let mounted = mounted_archive(&state, &archive_id)?;
+    let conn = database::open_or_initialize(&mounted.archive_path)?;
+    let caller_bits = auth_to_caller_bits(&auth);
+    Ok(Json(archive::list_child_entries(&conn, &entry_uid, caller_bits)?))
+}
+
 async fn search_entries_handler(
     State(state): State<AppState>,
     auth: AuthUser,
@@ -902,10 +918,11 @@ async fn capture_handler(
                     notes_str = serde_json::Value::Object(notes_map).to_string();
                     Some(&notes_str)
                 };
+                let job_status = if result.status == "completed" { "completed" } else { "failed" };
                 database::update_capture_job_status(
                     &conn,
                     &job_uid_bg,
-                    "completed",
+                    job_status,
                     Some(&result.run_uid),
                     None,
                     notes,