Add startup re-import queue to apply importer fixes to signed rounds

The loan-aware NAV fix (0.2.47) only affects new imports; an already-signed
quarter keeps its old holdings until re-imported. Add a boot-time queue: an
operator stages an eNAV plus a small JSON descriptor under
data/pending_reimports and the app re-imports it on startup via the same code
path as the admin Import screen, then removes the processed files. Guarded so a
queue problem never blocks boot. Bumps the package to 0.2.48.

Used to refresh SATS Credit Fund LP Q4 2025 to its full NAV including the
Fold Holdings loan.

backend/ten31portal/main.py

@@ -1,5 +1,6 @@
 """Ten31Portal FastAPI application."""
 
+import logging
 import os
 from contextlib import asynccontextmanager
 from pathlib import Path
@@ -41,6 +42,13 @@ async def lifespan(app: FastAPI):
     run_migrations()
     from ten31portal.storage import ensure_docs_dir
     ensure_docs_dir()
+    # Drain any operator-queued eNAV re-imports (e.g. to apply an importer fix to a
+    # signed round). Guarded so a queue problem can never block the app from booting.
+    try:
+        from ten31portal.pending_reimports import process_pending_reimports
+        process_pending_reimports()
+    except Exception:
+        logging.getLogger("ten31portal").exception("pending re-import sweep failed")
     yield