fix(sec): alert when a filing gap's reprieve lapses instead of re-pausing quietly

An escalated gap stops pausing setups while the issuer's own fundamentals are
still recent. That reprieve ends on its own — the stored filings age past
GAP_GATE_RECENT_FILING_DAYS, or a newer gap arrives and the all-escalated
condition fails — and nothing reported either, because filing_gap_aged only
escalates gaps whose escalated_at is NULL and so never fires twice for the same
gap. For the 43 issuers behind the previous commit that lands around
2026-10-26, when their late-April filings age out together.

sec_filing_gaps.exempted_at (migration 034) makes the transition observable:
stamped quietly while the issuer is exempt, cleared when the exemption lapses,
and the clear is what raises filing_gap_repaused — once per lapse, re-arming if
the issuer's data recovers and ages out again. A gap that was never exempt has
no transition and stays silent; it is simply still paused, which
filing_gap_aged already said.

gap_exempt_ciks is public so the importer alerts on membership changes in
exactly the set the gate reads, rather than restating the rule.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016Lo99z3jWqu9X9ueBU3Z3D

app/services/fundamentals_quality_service.py

@@ -70,13 +70,16 @@ async def active_gaps(
     return list((await db.execute(stmt)).scalars().all())
 
 
-async def _gap_exempt_ciks(
+async def gap_exempt_ciks(
     db: AsyncSession, gaps: list[SecFilingGap]
 ) -> set[str]:
     """CIKs whose gaps have stopped pausing setups (see GAP_GATE_RECENT_FILING_DAYS).
 
     Every one of a CIK's active gaps must be escalated: one fresh gap alongside an
     old one still means a filing we might yet ingest, which is worth pausing for.
+
+    Public because the importer alerts on this exact transition (a CIK dropping
+    out of this set is a pause coming back on) and the rule must not exist twice.
     """
     by_cik: dict[str, list[SecFilingGap]] = defaultdict(list)
     for gap in gaps:
@@ -135,7 +138,7 @@ async def blocked_reasons_by_cik(
     gaps = await active_gaps(db, ciks)
     # Escalated gaps on issuers that still have recent fundamentals no longer
     # pause setups, on either path below — the summary mirrors the same filings.
-    exempt = await _gap_exempt_ciks(db, gaps)
+    exempt = await gap_exempt_ciks(db, gaps)
     reasons = {
         gap.cik: "sec_filing_gap" for gap in gaps if gap.cik not in exempt
     }