fix(sec): 13F-HR parser — guard zero total_value, preserve XML entities

[RadioOrc]

fix(sec): 13F-HR parser — guard zero total_value, preserve XML entities

Why

Two independent bugs in openbb_sec/utils/parse_13f.py, both verified against live EDGAR filings (details + repro in the two linked issues):

1. Empty filings crash. Managers with no reportable holdings file a single placeholder row (value=0). total_value is then 0, weight = 0/0 = NaN, .replace({nan: None}) turns it into None, and the required weight: float field fails validation — the whole fetch raises ValidationError. Repro: CIK 1562087 (Thiel Macro), any quarter since 2025-Q4.

2. & silently dropped from names. The parser soups the entire SGML-wrapped Complete Submission TXT, which is not well-formed XML; lxml recover mode drops character entities, so S&P500 EQL WGT becomes SP500 EQL WGT with no error. Every filer holding S&P ETFs is affected every quarter. Repro: CIK 1536411 (Duquesne), 2026-03-31.

What

• parse_13f_hr: extract the embedded well-formed <XML> blocks (form header + information table), strip their <?xml?> declarations and reassemble under a synthetic root before parsing — strict XML path, entities preserved. Bare-XML inputs pass through unchanged.
• parse_13f_hr: guard the weight division — weight = ... if total_value else 0.0.

No public API change; SecForm13FHRData model untouched.

Testing

Against live EDGAR (openbb-sec 1.6.6 == 1.6.7 == main for the affected lines):

• Empty filing (CIK 1562087, 2026-03-31 and 2025-12-31): no longer raises; returns placeholder row with weight=0.0.
• Normal filing (CIK 1536411, 2026-03-31, 70 positions): all & preserved (S&P500 EQL WGT, Ishares S&P Gsci Commodity-, State Str Spdr S&P 500 Etf T), sum(weight) == 1.0 exactly, values/shares byte-identical to a direct parse of the standalone information-table XML.
• Cross-checked 14 filings across 7 institutions (incl. options positions with putCall, and a $1000s-convention filer) — field-level identical to an independent parser fed the standalone XML.

Fixes #7618 and #7619.

[CLAassistant]

All committers have signed the CLA.

[RadioOrc]

recheck