fix(ingestion,frontend): show live counter immediately on run start

Two issues with the initial implementation:
- Counter only appeared after the first SSE event arrived (scholarProgress null
  kept the v-else static template showing until a scholar completed)
- First events were often dropped because the EventSource hadn't subscribed yet

Fix:
- Backend: emit an initial scholar_progress kickoff event (0/0/N) at the
  start of run_scholar_iteration so the frontend receives total early
- Frontend: gate on isLikelyRunning alone (not scholarProgress); use optional
  chaining with fallbacks so "0 / … visited · 0 finished" shows immediately
  when a run starts, before any SSE events arrive

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/services/ingestion/scholar_processing.py

@@ -420,6 +420,7 @@ async def run_scholar_iteration(
             {"visited": visited, "finished": finished, "total": total},
         )
 
+    await _emit()
     first_pass_cstarts = await _run_first_pass(
         db_session,
         scholars=scholars,