fix(bdc): is_active checks a dropped BDC's own filings once its report row expires

[dgunning]

Bead edgartools-huul (salvaged from closed PR #1380).

Problem

Since #1146 the BDC register combines the last three SEC BDC reports and keeps each registrant's newest row. The 2026 report dropped 22 registrants, including Ares Capital, Gladstone Capital, Great Elm and Goldman Sachs Private Credit. Their 2025 rows are dated around 2025-05-29 and leave the 18-month window around 2026-11-29. After that, is_active would have returned False for BDCs that file every quarter.

Fix

Rows now carry in_latest_report, and is_active decides like this:

Report row	Result
inside the 18-month window	True, no request
from the newest report, outside the window	False: SEC's own current snapshot (the 1995-dated dormant registrants)
from an older report, outside the window	the company's newest filing date from its submissions JSON, cached per CIK

That means at most 22 requests per session today, not 52 (one per stale row). If SEC can't be reached, is_active falls back to the report row with a warning. Any other error propagates rather than quietly reading as "inactive". An explicit get_bdc_list(year=...) older than the newest report is treated as a snapshot of that time.

PR #1380's version exposed the window rule as a helper for callers but left is_active reading the stale row.

Verification

• Offline (fast): the module clock is frozen at 2026-12-01. There are tests for each branch, the unreachable fallback, other errors propagating, the register flag including explicit years, and parsing the submissions JSON. Every new test fails against main.
• Live, also on 2026-12-01: ARCC is in_latest_report=False with a row dated 2025-05-29, its own latest filing is on or after its 2026-07-29 10-Q, and is_active is True. MAIN is in the latest report and active.
• The get_latest_bdc_report_year() treats a 200 as a complete report, and the 2026 one is missing ARES CAPITAL CORP #1146 regression tests pass.
• test-fast: the only failure is the dt1f1 20-F test, which also fails on main.

🤖 Generated with Claude Code