fix(5.19): corectii UX/retentie held (findings #2-#6 /code-review high)

#2 Filtrul "doar tinute" (held=1) devine persistent: hidden #f-held in
   #filtre-trimiteri sincronizat prin OOB din _submissions.html + paginare
   pastreaza held=1; chip "Doar tinute manual / Arata tot" ca off-switch.
   Param `held` schimbat la str (held= gol nu mai da 422 la coercion).
#3 Banner bulk "Trimite toate (N)" extras in _bulk_held_banner.html si
   re-randat prin OOB (#bulk-held-banner-wrap) la fiecare reincarcare a listei
   -> nu mai ramane stale dupa eliberari (count revine la 0).
#4 tools/carantina_held seteaza purge_after (blocked_retention_days) pe randurile
   carantinate -> PII nu mai sta la nesfarsit (purge_expired le poate sterge).
#5 Panoul de detaliu marcheaza randul tinut (eticheta amber) si ofera buton
   "Trimite acum la RAR" (paritate cu randul din lista).
#6 expire_held seteaza purge_after=now-1s -> randul expirat e purjabil in ACELASI
   ciclu (purge_expired foloseste comparatie stricta), nu la ciclul urmator.

Teste noi: stickiness held + banner OOB + detaliu buton (test_web_auto_send),
purge_after carantina, purge acelasi-ciclu (test_worker_held). 1541 passed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_carantina_held.py

@@ -63,6 +63,12 @@ def test_carantineaza_rand_tinut(env, capsys):
     r = _row(conn, sid)
     assert r["status"] == "error"
     assert r["rar_error"] == "ROLLBACK_QUARANTINE"
+    # /code-review #4: randul carantinat primeste purge_after (altfel PII ar sta la nesfarsit,
+    # purge_expired sterge doar randuri cu purge_after setat).
+    assert r["purge_after"] is not None
+    assert conn.execute(
+        "SELECT purge_after > datetime('now') AS ok FROM submissions WHERE id=?", (sid,)
+    ).fetchone()["ok"] == 1
 
 
 def test_dry_run_nu_modifica(env, capsys):